Merge remote-tracking branch 'nobled/wayland-fixes2'

Merge remote-tracking branch 'nobled/wayland-fixes2'

* nobled/wayland-fixes2:
  wayland: fix shm buffers
  wayland: set renderable type on dummy surface
  wayland: check for egl extensions explicitly
  wayland: fall back to shm buffers if drm fails
  wayland: add shm buffer code
  wayland: make buffer handling generic
  wayland: really fix buffer format selection
  wayland: fix pixel format
  wayland: clean up buffer creation code
  wayland: don't require the surfaceless extensions
  wayland: check for API-specific surfaceless extension
  wayland: fix GLES context creation
  wayland: use EGL_NO_SURFACE
  wayland: update to new api
  wayland: fix connecting to default socket
  fix ClutterContainer docs