contrib/golang: Initial golang bindings

We were considering using this for Docker integration, but we may end
up going a different architectural path.  Anyways, it doesn't hurt to
have the bindings in here - they can do a few things.

I decided to fork some of the core code from
https://github.com/dradtke/gotk3 because...well, what we really need a
GIR-based core generator but I didn't want to start on the fully
correct thing until we knew we wanted it, and this was a quick hack.

Also, let's make a `contrib/` directory for things like this.

contrib/golang/COPYING

@@ -0,0 +1,17 @@
+Portions of this code are derived from:
+
+https://github.com/dradtke/gotk3
+
+Copyright (c) 2013 Conformal Systems LLC.
+
+Permission to use, copy, modify, and distribute this software for any
+purpose with or without fee is hereby granted, provided that the above
+copyright notice and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.