Ffmpeg-quality-metrics

* Fix detection of libvmaf model dir, fixes 34.

* Re-add old PKL models.

* Make docker a bit more quiet.

* Add option to keep temporary files.

* Always pick latest dockerfile version for docker_run script.

* Improve dockerfile build.

* Create FUNDING.yml.

* Update badge link.

* Add python_requires to setup.py.

* Fix README.

* Fix README.

* Change CLI syntax, add VIF filter.

Move CLI syntax to a more flexible format for selecting metrics.
This is not backwards-compatible, so a major release.
Add the VIF filter.

* Fix bug if VMAF is the only metric.

* Update docs.