The output_id is more of an opaque identifier for the monitor, based on
its underlying ID from the windowing system. Since we also use the term
"output_id" for the output's index, rename our use of the opaque cookie
"output_id" to "winsys_id".
Advertise the scale factor on the output and transform pointer and damage
events as well as input and opaque regions for clients
that scale up by themselves i.e use set_buffer_scale.
We do not scale any 'legacy' apps yet.
https://bugzilla.gnome.org/show_bug.cgi?id=728902
Right now this just has all of the files in one directory. We'll
be introducing more structure to this in the future, and build
a proper backend system.
