Implement support for display on Wayland compositors

Implemented initial support for display and input on wayland compositors. The following items should work fine:
 * Display, frame refresh
 * Detecting and selecting different output modes
 * Mouse input (buttons, wheels, motion, cursor hiding)
 * Keyboard input (key repeat)

The following items are not implemented yet
 * Dirty regions (requires core work to support EGL_EXT_buffer_age)
 * Comprehensive test framework (would rather do some more refactoring on the windowing system backend before implementing that)

Screenshot:
![wayland-on-weston-on-x](https://f.cloud.github.com/assets/775309/803048/3e5c5240-ede2-11e2-9fb4-f81573a01bfd.png)