In order to eventually support multilpe GPUs with their own connectors,
split out related meta data management (i.e. outputs, CRTCs and CRTC
modes) into a new MetaGpu GObject.
The Xrandr backend always assumes there is always only a single "GPU" as
the GPU is abstracted by the X server; only the native backend (aside
from the test backend) will eventually see more than one GPU.
The Xrandr backend still moves some management to MetaGpuXrandr, in
order to behave more similarly to the KMS counterparts.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
Instead of passing it around or fetching the singleton, keep a pointer
to the monitor manager that owns the CRTC. This will eventually be
replaced with a per GPU/graphics card object.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
Convert MetaCrtcMode from a plain struct to a GObject. This changes the
storage format, and also the API, as the API was dependent on the
storage format.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
Turn MetaCrtc into a GObject and move it to a separate file. This
changes the storage format, resulting in changing the API for accessing
MetaCrtcs from using an array, to using a GList.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
