Fix password change system
At the moment, when signing up there is no limit to password length, but when changing a password, it is limited to 20 characters. This results in the "old" password not being recognised correctly, presumably as it's looking for a password of maximum 20 characters.
So if you create a password with more than 20 characters as your first password, you can't change it without logging out and doing "forgotten password". Rubbish!