Run tests on Node 8 by default, add Node 7 to portability suite

Add artifact builds for Node 8

1.4.x branch cut, version bump PR

Master 1.3.x upmerge

Make jobset more eintr resilient

Get rid of flakey asserts in num_watchers test

C# add microbenchmarks project

Remove uneeded ref/unref

Fix sanity

clang-format and include guard fix

Improve contributing guidelines

Fix Python reflection arguments

Add more null checks to call methods

Fixes #9542

bump version to 1.3.6

Fix transitive inclusion of native libs in C# nugets

Remove the section for b64 encoded trailers.

Remove the section for b64 encoded trailers. As gRPC-Web uses CRLF to separate the trailers in the trailers frame, a binary trailer need to reserve in a base64 encoded format for their values. This cannot be skipped even base64 is applied on the whole trailers frame per client's request via content-type: application/grpc-web-text.

Intrusive hash map