Merge branch 'master' of github.com:grpc/grpc into cpp_docs

src/compiler/csharp_generator.cc

src/compiler/csharp_generator.h

src/node/ext/call.cc

src/node/index.js

src/node/interop/interop_client.js

src/node/src/client.js

src/node/src/metadata.js

src/node/src/server.js

src/node/test/metadata_test.js

src/node/test/surface_test.js

src/python/grpcio/grpc/_links/service.py

src/python/grpcio/grpc/framework/core/_end.py

...io_test/grpc_test/_core_over_links_base_interface_test.py

...c_test/_crust_over_core_over_links_face_interface_test.py

...python/grpcio_test/grpc_test/_links/_transmission_test.py

src/python/grpcio_test/grpc_test/test_common.py