Sanitizing master.

[support PHP7] control code by version of PHP macro

Establish Objective C end-to-end core test with Cronet

Added LB diagram and some more detail

Updated outdated comment about uchannels

minor changes. cannot assume hostname unchanged

Fix typos in config_protobuf.h

Reduce the number of unnecessary allocations

Grpc args doxygen

Python: fix spell error by pyflakes found

Add latency profiling from 'important' marks

Allows seeing directly how long was spent:
- running up to putting bytes on the wire
- between sending and receiving
- between receiving and finishing

Collapse fixture into CoreCronetEnd2EndTests.m so that individual test cases can be run, instead of only allow running the entire fixture

Fix of Issue #7181 documentation and Objective C code

Rename h2_ssl.* to h2_ssl_cronet.* and add static specifier to chttp2_tear_down_secure_fullstack in h2_ssl_cronet.m

Fix arguments for calls to Ruby's `Time.at`

C style guide updates

Generate html report for perf tests

Add clientSuccess and serverSuccess to BQ schema