This version-2 API splits up and renames parts of the version-1 API.

Some initial unit tests were added.

The code is now built and tested on Linux, Windows, and Mac (in
addition to Android, which is where it's being used).

Memory leaks were fixed and some memory/list-management TODOs were
also dealt with (associated with an Android bug).

Some review items deferred.  See: angleproject:2993

Bug: angleproject:2794
Bug: b/113346561
Change-Id: Iff307f9347fb05a733fe96b6774fb32d36e25590
Reviewed-on: https://chromium-review.googlesource.com/c/1291837Reviewed-by: Ian Elliott <ianelliott@google.com>
Reviewed-by: Yuly Novikov <ynovikov@chromium.org>
Commit-Queue: Ian Elliott <ianelliott@google.com>