Merge release-0_13 into master

Fix memory leak: keep all resolver calls under the same lock

Fix memory leak if call is already cancelled

Fix comparison direction - fixes timer_list_test flakiness

Fix typo

Obvious in hindsight, if the cas failed, we still created the subchannel
call object and then left it dangling.

Fixes a leak observed on master in the past 48 hours.

Updated main examples README to link to main docs and quickstarts

Doc Fixit: Clarifying how to install for gRPC C++

Doc Fixit: mention how to get protoc compiler in base INSTALL.md

Doc Fixit: PHP update readme

Disable profiling in qps_worker for now

Fix copyright (and master sanity)

Set grace=0 to server stop in route_guide

Add test_lite custom command for parallel test running.

Add self as SoC mentor

be a potential mentor if needed.

Put back the gflags/gtest requirement to doc

Potential fix for race condition exposed by Node