Add normalization (and comment) to hash of theory

Created by: scarlehoff

The normalization was missing from the hash.

I don't think this would've generated a bug anywhere because I don't think we would ever have the same fktable using two different normalizations for two different variants, but better safe than sorry.

I've also added the comment to the hash because, again, if someone is really going through that trouble maybe tehy would actually want the two dataset-theories be considered as separate object and not cached.