Provide better hashes for modfiles

[leper]

Currently the only checksum available for files is md5.

It would be nice if there's a checksum available that wasn't considered broken in the last century.

SHA-3 would be nice.

[intenscia]

Which hashes do your favorite package managers use?

At the moment md5 is provided because the primary aim is to verify the file download is complete. Collisions are not really a consideration.

[leper]

They handle that by signing files, but among the things used for those are BLAKE2, SHA256 and I guess if you start looking you are going to find more easily.

I guess BLAKE2 could be interesting given that it tends to be quite fast. I'd probably not start using SHA-2 when SHA-3 is already out there, but the same applies to MD5.

[intenscia]

I saw some recommendations for BLAKE2. Will look into it.