Factored Conformance and Benchmark test messages into shared test schema. (#1971)

* Factored Conformance test messages into shared test schema.

* Updated benchmarks to use new proto3 message locations.

* Fixed include path.

* Conformance: fixed include of Python test messages.

* Make maven in Rakefile use --batch-mode.

* Revert changes to benchmarks.

On second thought I think a separate schema for
CPU benchmarking makes sense.

* Try regenerating C# protos for new test protos.

* Removed benchmark messages from test proto.

* Added Jon Skeet's fixes for C#.

* Removed duplicate/old test messages C# file.

* C# fixes for test schema move.

* Fixed C# to use the correct TestAllTypes message.

* Fixes for Objective C test schema move.

* Added missing EXTRA_DIST file.
diff --git a/python/setup.py b/python/setup.py
index 524a312..ef1a31b 100755
--- a/python/setup.py
+++ b/python/setup.py
@@ -78,6 +78,7 @@
 def GenerateUnittestProtos():
   generate_proto("../src/google/protobuf/any_test.proto", False)
   generate_proto("../src/google/protobuf/map_unittest.proto", False)
+  generate_proto("../src/google/protobuf/test_messages_proto3.proto", False)
   generate_proto("../src/google/protobuf/unittest_arena.proto", False)
   generate_proto("../src/google/protobuf/unittest_no_arena.proto", False)
   generate_proto("../src/google/protobuf/unittest_no_arena_import.proto", False)