+ all tests pass,
- but there are a couple of workarounds
- tests are flaky

Make warnings errors when building Python tests.

Update the Status API

Added flags support to grpc_op.

Add PHP timeout interop test

Fix NPE for trying to add metadata to error when it was nil

Make run_jenkins.sh actually fail on failure.

Add PHP to jenkins

only build unbroken tests in Windows run_tests.py

Fix upstream merge conflicts

Remove failing globs from examples and tests

Simplify metadata usage

Revised the state machine.

Fix docs on gpr_slice_unref.

Fix docs on grpc_op_type.

include string_util.h for the prototype of gpr_strdup and fix a typo.

Fixes two warnings in log_win32.c under msvc2015
log_win32.c(109): warning C4013: 'gpr_strdup' undefined; assuming extern returning int
log_win32.c(109): warning C4047: 'return': 'char *' differs in levels of indirection from 'int'

and corrects a typo in an error message

Which includes its propagation to grpc_ioreq and validation mechanisms for checking that only known bits are set ot in).
Also added an internal flag (GRPC_WRITE_INTERNAL_COMPRESS) mask for its use in signaling compressed messages.