Shifted from CacheTask to functionality built into RenderBackend. It was
a lot easier to control behavior this way without having to juggle a ton
of threads and race conditions.
Could likely be multithreaded further.
Ensures their thread gets changed along with the viewer. The project
gets loaded/created in a background thread so the GUI can remain
responsive, and is then moved to the main thread for intended event
handling. However if the caches aren't parented, the hierarchy breaks
and the caches remain in a thread whose event loop is quickly destroyed.
Now that they're parented, events can be properly queued on them once
again.
Implemented a smarter auto-cache that's context sensitive. Caching will
automatically pause when playback begins or values are being changed and resume
when inactive.
itsmattkc