Enable a user to test and debug multi output configurations on Wayland
without having the available hardware by enabling some basic
configuration of the dummy monitor manager.
Currently available configuration options are:
MUTTER_DEBUG_NUM_DUMMY_MONITORS - to set the number of monitors
MUTTER_DEBUG_DUMMY_MONITOR_SCALES - to configure the monitor scales
See src/backends/meta-monitor-manager-dummy.c for detailed description
of the available configuration parameters.
https://bugzilla.gnome.org/show_bug.cgi?id=747089
To make the nested compositor mode work again after "backends/native:
Calculate the output scale in here", set the scale when creating the
dummy output.
https://bugzilla.gnome.org/show_bug.cgi?id=745401
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".
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.
