Bugfix: TRConfiguration.waitForProfiler() sets wrong cache var.
Moved getNavSystem and getHudSystem to Game.
Added loadingMode to BackdropSystem.
Removed auto-activation of RenderableSpacePartitioningGrid s.
Cleanup.
Removed CloudSystem's direct setting of Fog color.
Added loading-screen support to HUDSystem.
Added loading-screen, deferred player activation, insertion of HUDSystem
from TR, flipping of laoding/gameplay modes.