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.
Made various changes and fixes to the task system:
- Tasks are built around QtConcurrent rather than QThread. Reduces
code complexity significantly.
- Task error reporting is now streamlined in both TaskManager and
TaskDialog.
- Moved ProjectImport/Save/LoadManager to the app/task folder