On Ubuntu /bin/sh is dash by default, this can cause
generate_descriptor_proto.sh fail to execute.

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).

This is a start to fixing issue #1212. It won't help for test protos,
conformance etc, but it will definitely be better than nothing, and
would have highlighted a change in descriptor.proto which broken C#
earlier.

Java files are moved to un-do the hack in the prevous commit, which
moved the java files to the original position for integration.

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.

Change-Id: I23dee1c1d27b6440658680e9c273b6250213123c

Change-Id: I97960f30d50b1635aa6c395377cd021ef5ebddd5

- Maps for C++ lite
- C++ Arena optimizations.
- Java Lite runtime code size optimization.

Change-Id: I7537a4357c1cb385d23f9e8aa7ffdfeefe079f13

C++ and Java.  See CHANGES.txt for more details.

  bash-only features, and /bin/sh is not a symlink to bash on all systems.
* If an input file is a Windows absolute path (e.g. "C:\foo\bar.proto") and
  the import path only contains "." (or contains "." but does not contain
  the file), protoc incorrectly thought that the file was under ".", because
  it thought that the path was relative (since it didn't start with a slash).
  This has been fixed.

committer: Jon Skeet <skeet@pobox.com>

protoc
- New flags --encode and --decode can be used to convert between protobuf text
  format and binary format from the command-line.
- New flag --descriptor_set_out can be used to write FileDescriptorProtos for
  all parsed files directly into a single output file.  This is particularly
  useful if you wish to parse .proto files from programs written in languages
  other than C++: just run protoc as a background process and have it output
  a FileDescriptorList, then parse that natively.

C++
- Reflection objects are now per-class rather than per-instance.  To make this
  possible, the Reflection interface had to be changed such that all methods
  take the Message instance as a parameter.  This change improves performance
  significantly in memory-bandwidth-limited use cases, since it makes the
  message objects smaller.  Note that source-incompatible interface changes
  like this will not be made again after the library leaves beta.

Python
- MergeFrom(message) and CopyFrom(message) are now implemented.
- SerializeToString() raises an exception if the message is missing required
  fields.
- Code organization improvements.
- Fixed doc comments for RpcController and RpcChannel, which had somehow been
  swapped.