Feature request: Allow using --check with --printf

[mariomadproductions]

Problem: If my hash file is created using my own --printf format, it seems like I am not able to check the file matches those hashes with just rhash alone.

Possible solution: Allow using --check with --printf. I.e. using those parameters together would make it parse the file using the printf format, and check all those hashes. I guess by default it should check size first, then the strongest hash, and abort if any don't match?.

I think in addition to this, if a hash function parameter is specified, e.g. --sha256, it should only check that one hash, rather than every hash in the file (if there are multiple). Or there could be a new parameter(s) for this.