Split X11 specific parts into MetaX11Display. This also required
changing MetaScreen to stop listening to any signals by itself, but
instead relying on MetaDisplay forwarding them. This was to ensure the
ordering. MetaDisplay listens to both the internal and external
monitors-changed signal so that it can pass the external one via the
redundant MetaDisplay(prev MetaScreen)::monitors-changed.
https://bugzilla.gnome.org/show_bug.cgi?id=759538
- Moved xdisplay, name and various atoms from MetaDisplay
- Moved xroot, screen_name, default_depth and default_xvisual
from MetaScreen
- Moved some X11 specific functions from screen.c and display.c
to meta-x11-display.c
https://bugzilla.gnome.org/show_bug.cgi?id=759538
