wayland: Add support for SDL_SetWindowFullscreen
wayland: Add support for SDL_SetWindowSize
wayland: Keep reading events until we get wl_output details

With the wl_registry change in 1.0 we need another roundtrip before we
get the wl_output modes.  Use a loop instead so we make sure to
read events until we get the output details.
Merge pull request #16 from krh/wayland

Wayland