introduce x google mux very draft indeed

This is initial x-google-mux support.  It's disabled by default
since it's very pre-alpha.

1) To enable it, reconfigure with --enable-x-google-mux

2) It conflicts with deflate-stream, use the -u switch on
   the test client to disable deflate-stream

3) It deviates from the google standard by sending full
   headers in the addchannel subcommand rather than just
   changed ones from original connect

4) Quota is not implemented yet

5) Close of subchannel is not really implemented yet

6) Google opcode 0xf is changed to 0x7 to account for
   v7 protocol changes to opcode layout

However despite those caveats, in fact it can run the
test client reliably over one socket (both dumb-increment
and lws-mirror-protocol), you can open a browser on the
same test server too and see the circles, etc.

Signed-off-by: Andy Green <andy@warmcat.com>
16 files changed