Include javadoc/source in Java release packages.

Also fixed javadoc errors.

[ci skip]

Added 3.0.0-beta-4 changelog.

Change-Id: I43f7e04a53d1445dfa86db310bdb18ceb446398c

Use public methods to fetch oneofs in generated code.

When building into frameworks, the generated code doesn't always have direct
access to the proto internals.  Instead of opening up the access, just use the
public method to fetch the correct oneof.

Fixes https://github.com/google/protobuf/issues/1789

Change-Id: Ic07a7c664930209974244c66885d672288982610

Exposes the currently registered extensions for a message and removes the internal sortedExtensionsInUse

Uses head version of rvm to avoid shell_update_session not found error

Fixes #1786 

Change-Id: I997012e7e9b58d9ec8b2f59429d71c98d81aa40d

Fix compatibility issues for the future GeneratedMessageV3 change.

Currently some public API methods are defined in GenreatedMessage.java
and they have a generric return type:
  class GeneratedMessage {
    class Builder<BuilderType extends Builder<BuilderType>> {
      public BuilderType setField(...);
      public BuilderType setExtension(...);
    }
  }
With these definitions, the compiled byte code of a callsite will have
a direct reference to GeneratedMessage. For example:
  fooBuilder.setField(...);
becomes:
  ##: invokevirtual // Method Builder.setField:(...)LGeneratedMessage.Builder
  ##: checkcast     // class Builder

This will prevent us from updating generated classes to subclass a
different versioned GeneratedMessageV3 class in the future (we can't do
it in a binary compatible way).

This change addresses the problem by overriding these methods directly
in the generated class:
  class Foo {
    class Builder extends GeneratedMessage.Builder<Builder> {
      public Builder setField(...) {
        return super.setField(...);
      }
    }
  }
After this, fooBuilder.setField(...) will be compiled to:
  ##: invokevirtual // Method Builder.setField:(...)LFoo.Builder

The callsites will no longer reference GeneratedMessage directly and we
can change Foo to subclass GeneratedMessageV3 without breaking binary
compatiblity.

The downside of this change is:
  1. It increases generated code size (though it saves some instructions
     on the callsites).
  2. We can never stop generating these overrides because doing that
     will break binary compatibility.

Change-Id: I879afbbc1325a66324a51565e017143489b06e97

Merge C# changes from master to 3.0.0-beta4

This also updates the version number to 3.0.0-beta4

We now just perform the optimization within AddRange itself.

This is a breaking change in terms of "drop in the DLL", but is
source compatible, which should be fine.

(Also fix a few more C# 6-isms.)

This fixes issue #1730.

Move to dotnet cli for building, and .NET Core (netstandard1.0) as target platform

This also updates the version number to 3.0.0-beta4

Update version number to 3.0.0-beta-4

Comment out lite conformance test.

The 'lite' generator flag is no longer supported.

* Improve exception throwing implementation in collections

* Implement RepeatedField.AddRange.

This fixes issue #1730.

* Optimize AddRange for sequences implementing ICollection

(Also fix a few more C# 6-isms.)

* Remove the overload for Add(RepeatedField<T>)

We now just perform the optimization within AddRange itself.

This is a breaking change in terms of "drop in the DLL", but is
source compatible, which should be fine.

Fix a <package>_FIND_VERSION_PRERELEASE being ignored

Remove the baseline files from the make dist file list.

https://github.com/google/protobuf/pull/1762 remove the files, but I forgot to
update Makefile.am to remove them.

Modify csharp README since there are now two NuGet packages

Remove unnecessary reflection call

This is the only call to TypeExtensions.IsValueType, so we can remove
that method, making the whole type conditionally compiled out for .NET 3.5