Turns out travis doesn't have the library dependencies to run a 32-bit
binary.

Change-Id: I5fadbcade2eb71c1e9ce21d90fa9459797df0e81

Change-Id: I991396ac6e51e32f3ab1daa501d625f34c3ecb04

Change-Id: Ib2bb5042deaabdf452d5be2ad1ce40d739ad8d1b

Also fixed javadoc errors.

[ci skip]

Change-Id: I43f7e04a53d1445dfa86db310bdb18ceb446398c

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

This includes all internal changes from around May 20 to now.

- Using custom URL for types in Any will no longer throw an
InvalidProtocolBufferException in JsonFormat
- Fixes #1128

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

Moving the files to their original location, so that opensource changes
can be picked during the internal merge. Those files will be moved into
the correct location after merging with internal code.

Note: do NOT merge this into master without the other internal
down-integration commit.

protobuf/java will become a parent pom that will contain two modules:

core - contains all of the code for the protobuf-java artifact
util - contains all of the code for the protobuf-java-util artifact

Also cleaned up various Maven warnings.

Change-Id: Ibb3fe6f919cc7ca0df91da5e1697ba33d259e433

Change-Id: I3daf32cb93dfe0fca38f8b48615ccfc307f748e9

"equals".equals("euqals") == false