* Added FindXCB.cmake script
* Added AutoPointer wrapper for automatically free'ing pointers
* Huge commit: Ported linux implementation of sfml-window to xcb
* Xcb is now used for window creation, event loop etc
* As GLX is linked to Xlib, that part of the implementation
still uses Xlib.
* Also, some keyboard related (such as XLookupString) stuff
is still Xlib, as xcb does not have it (yet?).
* Replaced some enums with the xcb equivalents
