Add hashes check for models

[PonteIneptique]

Models might be updated, and their update might break with a general update of pie-extended.

To avoid situation where users would not understand why the model does not work anymore, it would be good to have for each downloadable file a list of allowed hashes (sha or md5) where:

• the first hash in the list (HASH[0]) is the latest model
• all other hash are deemed compatible with the current version.

On tag function, have a --no-hash-check function for people wanting to use custom models.