Stop creating EncryptionMethod objects excessively

[ljacqu]

See PasswordSecurity -> each time a player wants to log in we emit an event and create an EncryptionMethod instance. In surely 95% of the cases it is fine if we just do this once for each HashAlgorithm setting. Introduce a configuration for this.

[ljacqu]

on reload any EncryptionMethod needs to be cleared, though, regardless whether the hashalgorithm property changes or not