[Nice] Farsight integration

[Dafydd Harries]

I've managed to make Nice integrate somewhat with Farsight, including making
calls via Telepathy, though in some cases the call seems to deadlock. I
haven't gotten around to debugging it yet. Here are the changes I made to
Nice, Farsight and Telepathy's Stream Engine:

http://people.collabora.co.uk/~daf/nice/

I've also written a tool to simplify the procedure of testing calls using
Telepathy on a local machine:

http://people.collabora.co.uk/~daf/callomatic.py

It might be nice to extend it to controlling calls on remote machines for
testing other scenarios.

-- 
Dafydd