Add the `nullable` qualifier to return types of Objective-C methods that
can return a nil due to errors. This change makes these methods
compatible with the Swift 2 try-catch syntax.

- Correct some cases sources were compiled into the static lib and the tests.
- Enable Xcodes code coverage support on the unittests.  We aren't complete on
  coverage, but having the data always there should make it easier to chip away
  at this going forward.
- Drop method in tests that isn't used, wire up a validator in another test.

- Correct impl by using helpers the message wiring does.
- Add unittests.

Fixes https://github.com/google/protobuf/issues/1716

Note: Breaking API change on the Dictionary classes.

The numeric value classes were using "Value" in the naming, but this silently
collided with the KVC category on NSObject; meaning KVC code could break up a
keypath and call these selectors with the wrong types leading to crashes (even
though the code all would compile cleanly).

- Rename the methods to use the "type" instead of literal "Value".
- Update all the impls and tests.
- Enable the warning that will catch issues like this in the future.

Fixes https://github.com/google/protobuf/issues/1616

Adds destination flag to xcodebuild to avoid possible flake errors

Also hotwires updating ruby as CocoaPods was crashing within a support library.

Fixes #1619 

Add more context to GPBCodedInputStream failures.
Have GPBMessage parsing apis extract out the GPBCodedInputStream information and expose it.
Update HeaderDocs with pointers to all error domains/codes.
Expand the unittests to cover the full set of errors reported.

Fixes https://github.com/google/protobuf/issues/1618

This is currently checking for the wrong class for enums
and NSMutableArray fields.

- Add generator constant for the default framework name.
- Add generator api for making the CPP symbol from the name.
- Add generator api to see if it is a bundled proto file.
- Output a CPP conditional and two imports for the core library headers.
- Add helper for generating the #import for file headers to deal with the
  framework imports.
- Add a reference from the unittests to a WKT to use that to inspect how
  imports generate.
- Update the podspec to define the CPP symbol and require pods 1.0 (or later).

Fixes https://github.com/google/protobuf/issues/1457

- Env solution doesn't seem to always work, use template pod files and copy
  them in place instead.
- Flush the pods cache before and after runs.
- Make pod install verbose to have the info incase something goes wrong.

Otherwise the projects have to be opened once to create user schemes for the
command line builds to work.

- Add an Xcode 6.3 created default iOS Project.
- Add an Xcode 6.3 created default OS X Project.
- Add Podfiles to for both that use Protobufs from within the tree.
- Add a script to run the tests (and cleanup) to help confirm the state of the
  Protobuf.podspec and sources.

Both methods weren't checking the has_bits (where the bools are stored), so
it resulted in invalid results.

Add a test that should shake out something like this in the future also.

proto2 syntax allows the first enum to have a non zero value. This means any
field using that default has a non zero default without having an explicit
default being set. So when deciding what runtime info is needed, don't rely
on an explicit default, always check that the values aren't zero.

Fixes https://github.com/google/protobuf/issues/1453

This seems to be some code evolution side effects. Back when there was a custom
string class, we couldn't really error when we finally saw the string was bad
so we had to return the empty string, but now that full validation is done
up front, it can error out.

NOTE: This is a binary breaking change as structure sizes have changed size
and/or order.

- Drop capturing field options, no other options were captured and other mobile
  targeted languages don't try to capture this sort information (saved 8
  bytes for every field defined (in static data and again in field descriptor
  instance size data).
- No longer generate/compile in the messages/enums in descriptor.proto. If
  developers need it, they should generate it and compile it in. Reduced the
  overhead of the core library.
- Compute the number of has_bits actually needs to avoid over reserving.
- Let the boolean single fields store via a has_bit to avoid storage, makes
  the common cases of the instance size smaller.
- Reorder some flags and down size the enums to contain the bits needed.
- Reorder the items in the structures to manually ensure they are are packed
  better (especially when generating 64bit code - 8 bytes for every field,
  16 bytes for every extension, instance sizes 8 bytes also).
- Split off the structure initialization so when the default is zero, the
  generated static storage doesn't need to reserve the space. This is batched
  at the message level, so all the fields for the message have to have zero
  defaults to get the saves. By definition all proto3 syntax  files fall into
  this case but it also saves space for the proto2 that use the standard
  defaults. (saves 8 bytes of static data for every field that had a zero
  default)
- Don't track the enums defined by a message. Nothing in the runtime needs it
  and it was just generation and runtime overhead. (saves 8 bytes per enum)
- Ensure EnumDescriptors are started up threadsafe in all cases.
- Split some of the Descriptor initialization into multiple methods so the
  generated code isn't padded with lots of zero/nil args.
- Change how oneof info is feed to the runtime enabling us to generate less
  static data (8 bytes saved per oneof for 64bit).
- Change how enum value informat is capture to pack the data and only decode
  it if it ends up being needed. Avoids padding issues causing bloat of 64bit,
  and removes the needs for extra pointers in addition to the data (just the
  data and one pointer now).

Add a compile test to confirm things are working as expected.

- Convert most of the core library headers over to HeaderDoc format.
- Switch the generated comments over to HeaderDoc.
- Create GPBCodedOutputStream_PackagePrivate and move some things into there
  that should be more internal.

- Extend GPB*ObjectDictionary to support generic syntax.
- Update the generator to output generics so the enclosed type is exposed for compiler checks.
- Use generics in a the public interfaces.
- Update the generated sources that are checked in.

Incase developers look at the tests for examples, have them rely on the
autocreators also.

Apple engineers have pointed out that OSSpinLocks are vulnerable to live locking
on iOS in cases of priority inversion:
. http://mjtsai.com/blog/2015/12/16/osspinlock-is-unsafe/
. https://lists.swift.org/pipermail/swift-dev/Week-of-Mon-20151214/000372.html

- Use a dispatch_semaphore_t within the extension registry.
- Use a dispatch_semaphore_t for protecting autocreation within messages.
- Drop the custom/internal GPBString class since we don't have really good
  numbers to judge the locking replacements and it isn't required. We can
  always bring it back with real data in the future.

- Let Xcode update the projects, schemes, and info.plists.
- Add workaround for shallow analyzer issues in current Xcode versions (deep analyze gets things correct).
- Tweak the Swift based tests to avoid warnings from Xcode 7's XCTest using optionals for autoenclosure results.
- No longer tag the ObjC iOS travis test as flaky, xctool seems to manage the simulator pretty well.

NS_ENUM changes defintion in Objective C++ based on the C++ spec being
compiled with, special case the one situation where it wouldn't support doing a
forward decl for the enum.

- Move up to 8.4 as the high simulator (assuming Xcode 6.4).
- Add cast to NSMutableDictionary so clang and resolve the selector.
- Add case for the newer static analyzer so it won't trigger a false warning.
- Update the "dictionary" interface to use "object" naming. Xcode 7+ has gotten
  more strict on the use of nonnull/nullable; combining that with the generic
  collection support; and the "dictionary" classes we created now collide with
  what the generic KeyValueCoding in the system headers triggering
  warnings/errors. Fix this and hopefully all future issue by renaming the
  methods to use "object" for the classes that have data types as objects
  instead of PODs. Taking this renaming hit now while ObjC is still in beta
  because it is a breaking change for any existing code.

This reverts commit 7366efd8.

Still some discussion about the api to expose the helpers with.

The previous two methods make it easy to transform between any and normal message.
unPackeTo will throw error if the type url in any doesn't match the type of the message to be transformed to.
is checks any's type url matches the give GPBMessage type.

Add the clang annotations to the objc library and generated code to help with Swift bridging and compiler checks.

- Add more to the ObjC dir readme.
- Merge the ExtensionField and ExtensionDescriptor to reduce overhead.
- Fix an initialization race.
- Clean up the Xcode schemes.
- Remove the class/enum filter.
- Remove some forced inline that were bloating things without proof of performance wins.
- Rename some internal types to avoid conflicts with the well know types protos.
- Drop the use of ApplyFunctions to the compiler/optimizer can do what it wants.
- Better document some possible future improvements.
- Add missing support for parsing repeated primitive fields in packed or unpacked forms.
- Improve -hash.
- Add *Count for repeated and map<> fields to avoid auto create when checking for them being set.

- Shouldn't need SRCROOT in the project since Xcode should be setting the working directory to where the project lives.
- Remove the packed/unpacked repeated enum field in the tests and update the code to handle the defaults.
- Move up the ignore to cover .DS_Store files in src also.

add starstar

- Style fixups in the code.
- map<> serialization fixes and more tests.
- Autocreation of map<> fields (to match repeated fields).
- @@protoc_insertion_point(global_scope|imports).
- Fixup proto2 syntax extension support.
- Move all startup code to +initialize so it happen on class usage and not app startup.
- Have generated headers use forward declarations and move imports into generated code, reduces what is need at compile time to speed up compiled and avoid pointless rippling of rebuilds.