[~] Deprecated : Tools::encrypt() && Tools::encryptIV

Those functions use MD5, which isn't considered "encryption", and are also used to hash things like passwords, which isn't safe anymore. This splits usage of those functions between `Tools::hash` and `Tools::hashPassword` and moves password-checking to a dedicated function, `Tools::checkPassword`.
[*] Security : Use phpass for the passwords.

This handles transparent upgrades of the passwords to the new format on login.