change user password

[chrismade]

there is already a function which detects default admin/admin and make user to change the password - so this might be a low-hanging-fruits to re-use that function to allow already logged-in users to change their password - it could be attached to the user name in the upper right corner (proposal) - I wasn't able to find a 'change password' function somewhere in system/console. If is it a bigger deal to implement - or re-use is not possible - pls set to close/wontfix