* Add Syntax enum and make file syntax checks check the enum
 * Made IsPacked a normal get method without ternary op
 * Moved IFieldAccessor.HasValue to IFieldPresenceAccessor
 * Change naming of GetIsExtensionsInitialized
 * Fixed stray text in summary text

Adjust APIs for extensions to properly return default values for extensions
Fix issues with IsInitialized and proto2 field reflection

* Compiler changes (extensions)

* Generated changes (extensions)

* Library changes (extensions)

* Adjusted a summary to indicate ContainingType can be null for extensions

* Compiler changes (custom option review + access level review)

* Generated code changes (custom options + access review)

* Library changes (custom options + access review)

* Support C# 6 with library changes

* Access HasValue by property

* Set access level of all extension classes to internal (revert in next PR)

* Added null checks to custom options

* Rebase on master and regenerate Conformance

* Removed second dictionary from ExtensionSet

* Rebased compiler changes

* Rebased generated code changes

* Rebased library changes + review changes

* Add more safety checks to extension accessors

* Remove instances where extension sets were unnecessarily allocated

* Remove cleared items from sets
Empty sets are now made null
IExtensionMessage -> IExtendableMessage

* Remove dead code from IExtensionValue impls

* Clean both repeated and single value extensions

* Add GetOrRegister method for repeated fields and allow clearing repeated extensions

* Add type safe ClearExtension methods, remove non-generic IExtendableMessage interface.

* Simplify ExtensionSet.TryMergeFieldFrom

* Rebase on master to resolve conflicts

* Fix Makefile.am

* Add ObjectIntPair to Makefile.am

Signed-off-by: Xiang Dai <764524258@qq.com>

* Compiler changes

* Generated code changes

* Library changes

* Compiler style changes

* Generated style changes

* Fix Windows build errors

* Implement changes from review

* Reintroduce proto2 check

* Compiler changes (required handling review)

* Generated code changes (required handling review)

* Library changes (required handling review

* Field presence rewrite (compiler changes)

* Field presence rewrite (generated code changes)

* Compiler comment

* IFieldAccessor.HasValue library implementation

* Remove Clear methods and default values from proto3 code (Compiler)

* Remove Clear methods and default values from proto3 code (Generated)

* Remove Clear methods and default values from proto3 code (Library)

* Fix distcheck error

* Rewrite default string values to use base64 and convert

* Library changes (IMessage2)

* Compiler changes (IMessage2)

* Generated changes (IMessage2)

* Rebased and regenerated

* Compiler changes (initialized extension)

* Generated changes (initialized extension)

* Library changes (initialized extension)

* Refactor MessageExtensions.IsRequired

* Move string default value creator and bytes default value creator back to seperate methods

* Dead code cleanup

* Fixed segmentation fault
Removed unused header method declarations

By default, unknown fields are preserved when parsing. To discard
them, use a parser configured to do so:

var parser = MyMessage.Parser.WithDiscardUnknownFields(true);

(Generated code changes in next commit.)

Now the generated code doesn't need to check for end group tags, as it will skip whole groups at a time.
Currently it will ignore extraneous end group tags, which may or may not be a good thing.
Renamed ConsumeLastField to SkipLastField as it felt more natural.
Removed WireFormat.IsEndGroupTag as it's no longer useful.

This mostly fixes issue 688.

(Generated code changes coming in next commit.)

Rename ThrowHelper to Preconditions and make it public - we'll want to use it from the generated code soon.

Additionally, change it to return the value passed, and make it generic with a class constraint.
A separate method doesn't have the class constraint, for more unusual scenarios.

We'll see what I've missed when CI fails...

Everything should now be consistent - the only difference between files is the year (aside from generated files).

Fixes issue #531.

This is mostly just making things internal instead of public, removing and reordering a bunch of code in CodedInputStream/CodedOutputStream, and generally tidying up.

- Make some members internal
- Remove a lot of FrameworkPortability that isn't required
- Start adding documentation comments
- Remove some more group-based members
- Not passing in "the last tag read" into Read*Array, g

Remove ICodedInputStream and ICodedOutputStream, and rewrite CodedInputStream and CodedOutputStream to be specific to the binary format. If we want to support text-based formats, that can be a whole different serialization mechanism.