wayland.compositor: CompositorToken is threadsafe
wayland.compositor: CompositorToken is threadsafe

Thanks to the refactor of wayland-rs, the CompositorToken can
be make Send/Sync again.

Fixes #66.

Smithay/smithay,Smithay/smithay,Smithay/smithay,Smithay/smithay,vberger/smithay,vberger/smithay