Update API usage, incorporate new features, and refactor a bit:
- Use new progress callback to show progress bar
- Use new frame info functions to get timecodes/keyframes instead of
manually decoding
- Use new tracklist API to show track selection dialogs
- Expose option of whether to apply RFF
- Show a warning when bestsource had to revert to linear decoding
- Reuse the swscale context across frames and ensure the format
stays constant
- Add xxhash wrap
- No longer mark the bestsource video provider as slow
Some of these got lost in the process before.
For now, default to 709 if the colorspace is unkown. More detailed
colorspace guessing can be added in the future.
