Add xrt_system and xrt_session
Builds on !2057 (merged) and !2069 (merged).
This MR adds xrt_system
and xrt_session
objects, documentation still needed. The changes was done so that events could flow directly from a session object instead of the compositor. Letting us more easily add space events.
Please take a look as I add documentation.
Edited by Jakob Bornecrantz