Spice backend for Weston

[Shvedov Yury]

Hello.

As part of my course work, I've developed spice backend for Weston (the 
reference implementation of Wayland compositor). Currently this uses
Wayland's pixman-based renderer, and shares rendered frames over spice
protocol. With my backend, it is possible to communicate with wayland
desktop using spice client.

Current implementation is proof-of-concept only. Only shm buffers are 
supported, and no attempt is made to optimize bandwidth. Performance is 
expectedly bad. The first goal was just to make it working, and now it 
works - at least if client and server are on the same physical host.

In future, I plan to utilize GL both for rendering and calculating 
difference between frames. With this approach I hope to get both 
full-functional desktop and minimize server and bandwidth requirements.

My code is available at
https://github.com/ein-shved/compositor-spice.git

Comments and/or bugfixes are greatly appreciated.

P.S.
I know that recently RDP backend was added to Weston.
I was not aware of that while working on my backend.
I hope it will be possible to share effort with that project to build 
better remote wayland solutions.