Removed proxy task and replaced with a true honest-to-god pre-cache for
footage. This footage is pre-cached to a sequence and therefore 100% ready
for use in it once the task is done.
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
Turned the two-step PCM transcode into one step and simplified/removed much of
the unnecessary infrastructure that supported it. This makes the code cleaner
and generally improves the code paths.
The import function was written early on in the rewrite as a multithreaded
background task that was considered somewhat flawed. While it worked for the
most part, there were possibilities of race conditions that could have
potentially been fatal, particularly since media could theoretically be
deleted while the import/probe tasks were running in the background.
With the save/load functions coming in, it became even more complicated as
projects may include metadata about the footage that can't be implemented
easily when the footage is imported/probed in the background. Making importing
a modal task fixes all of these issues, it's still done in a background thread
to not hang the GUI thread, but the GUI thread can be briefly "paused" in a
user friendly way so that all these functions can be safer.