The order and way include macros were structured was chaotic, with no
real common thread between files. Try to tidy up the mess with some
common scheme, to make things look less messy.
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
Move code dealing with Xrandr MetaCrtcs and related functionality to its
own file. Eventually, MetaCrtcCrtc should be introduced, based on
MetaCrtc, and this commit is in preparation for that.
https://bugzilla.gnome.org/show_bug.cgi?id=785381
