Merge github.com:grpc/grpc into bwest

CMakeLists.txt

build.yaml

examples/csharp/helloworld/generate_protos.bat

examples/php/composer.json

examples/php/greeter_client.php

examples/php/helloworld.pb.php

examples/php/helloworld.php

examples/php/helloworld_grpc_pb.php

examples/php/route_guide/route_guide.pb.php

examples/php/route_guide/route_guide.php

examples/php/route_guide/route_guide_client.php

examples/php/route_guide/route_guide_grpc_pb.php

include/grpc/census.h

src/core/ext/census/gen/trace_context.pb.c

src/core/ext/census/gen/trace_context.pb.h

src/core/ext/census/trace_context.c

src/core/ext/census/trace_context.h

src/core/lib/iomgr/tcp_client_windows.c

src/core/lib/support/time_windows.c

src/csharp/Grpc.Core.Testing/.gitignore