WiP: Cursor spy
This implements a protocol for spying on cursors on a given output. This is needed for implementing client side cursor rendering in VNC. See https://github.com/rfbproto/rfbproto/blob/master/rfbproto.rst#cursor-pseudo-encoding
This feature significantly improves user experience on high latency VNC.
This implementation currently assumes that the pixel format read from cursor textures is ARGB8888. This will be fixed later, I just want some feedback on the protocol.
wayland-protocols MR is here: wayland/wayland-protocols!39 (closed)