run_tests.py will start a server (if it's not running, or if the running
port server mismatches the 'current' one) that serves ports to use for
tests. The server is left running after run_tests.py finishes, so that
in environments such as Mac and Windows where tests run unshielded from
each other, we don't start jumping on already used ports.

Currently the oauth2 variant of these tests is disabled. Will work with
@jboeuf to figure out how to turn them on.

Currently, if two threads call grpc_completion_queue_pluck on the same
completion queue for different tags, there is a 50% chance that we
deliver the completion wakeup to the wrong poller - forcing the correct
poller to wait until its polling times out before it can return an event
up to the application.

This change tweaks our polling interfaces so that we can indeed wake a
specific poller.

Nothing has been performance tuned yet. It's definitely sub-optimal in a
number of places. Wakeup file-descriptors should be recycled. We should
have a path that avoids calling poll() followed by epoll(). We can
probably live without it right at the second though.

This code will fail on Windows at least (I'll do that port when I'm in the office and have a Windows
machine).

appropriate

Initial plumbing work; needs tests and more client_channel
implementation.

Rename ThreadPool -> FixedSizeThreadPool to allow for later introduction
of DynamicSizeThreadPool

Use it to validate that arithmetic on time types makes even some vague
kind of sense.

The nuget command line tool can't find which solution we want to restore packages on. The documentation needs some update.

With run_test.py, we need a tools target now. Let's fake it for Windows so we can at least build.

Tests not yet included.