This commit makes the wayland backend search through the config for
[output] sections with names starting with "WL" and create outputs
accordingly. Outputs created due to the config file support mode, scale,
and transform parameters. It also listens for the --output-count
command-line option.
This brings the wayland backend almost up to par, in terms of functionality
with the X11 backend.
Signed-off-by: Jason Ekstrand <jason@jlekstrand.net>