Add support for more password hash types (patch)
here is a little patch that allows (email) users to authenticate with legacy des based crypt hashes. we needed this when migrating an existing user database to ispconfig without havig users to change ther passwords.
it adds the function cryptcheck() that depending on the format of the hash, validates the password.
right now it only allows $1$ (MD5), $5$ (SHA256) and DES hashes and unsalted plain MD5. it might be better to generalize this fnuction further to always just try crypt() first and fall back to md5 check if that fails.