Auth context python

Finish pumped streams: should alleviate infinite hang

Roll up of all new polling engines

Stop checking for pre-c++11 compilers since these are no longer supported

Lower the level of a log message to INFO

Properly filter the end2end tests

Fix port server in internal CI

Fixing nits in core.

supported

Remove gcc-4.4 and 4.6 from portability tests

Revert "Documentation on how to write unit tests using auto-generated mocked stubs."

Documentation on how to write unit tests using auto-generated mocked stubs.

Add to Codegen Interface, Refactor Proto Serialization

Refactor client logic into superclass with generic methods, improve documentation

Add some casts for C++ compatibility

Fixes for ubsan C++ build

Fix small message streaming ping-pong write count regression

Fix python artifact build

Add Unbalanced Unary Benchmark

Increase error threshold for too many writes