Some globals are static and it doesn't make sense to destroy them before
the wl_display. For instance, wl_compositor should be created before the
display is started and shouldn't be destroyed.
For these globals, we can simplify the code by removing the destructor
and stop keeping track of wl_resources (these will be destroyed with the
wl_display by libwayland).
Changed the contribution guidelines to be more consistent with the style
that wlroots has evolved into, and removed some duplicate information
that already exists in the kernel style.
Simon Ser
Armin Preiml
Genki Sky
Drew DeVault
Scott Anderson