Allow different hash function

When tagging video files, the md5sum function takes quite a whileon big files (over a network for example).
Have you think about using BLAKE3 checksum instead?

We are using standard Net facilities for calculating hashes and Net doesn’t support many fancy algorithms. I will note this as a valid request though.

It won’t make a difference for network-based files unless we’re talking about Gigabit Ethernet here.