* Refactor: Better ffmpeg pipe handling + more info in --version
* Update dependencies
* Better documentation in `--help`
* Include git commit hash and more info in `--version`
* Add `-k` as shorthand for `--keep`
* Do not pass `ffmpeg_pipe` around everywhere
* Use macro to generate encoder bit depth functions
* Fix documentation in README
* Fix some clippy warnings
* Refactor into `Input` type for handling vapoursynth input
Fixes several issues, namely `--vmaf` not working on vapoursynth input
as well as unifying the VMAF interface, which also results in
`--vmaf-threads` being passed correctly to `--vmaf`, which is massively
faster now as a result. If `--vmaf-threads` is not specified, then
the number of detected CPU threads is used for `--vmaf`.
Additionally, VMAF plots are rendered as SVGs now, which also removes
some dependencies since we don't use the bitmap backend at all anymore.
* Small cleanup: more consistent usage of `as_path`
