Implement wl_output and send geometry and mode events
Shrink surfaces on panel click

This is mostly just an experiment. I added a compositor method to
provide a GList of all the current surface actors, which can then
be manipulated by the shell with clutter. For now, when the panel
is clicked, all the surface actors are shrunk and lined up in a
grid (all values are still hard-coded). Also, I scrapped all the
various shell header files and merged them into shell.h.