Partially refactors acp_board for the new authentication interface.
Leaves some questionable if statements in the file.
Modifies the interface to correctly impletment the acp() method.
Modifies each provider to comply with the above mentioned interface
modification.
PHPBB3-9734
Replaces short tags with long tags.
Fixes the interface to be an interface and not class in the file.
Removes unnecessary include_once from auth.php.
PHPBB-9734
Provides basic documentation of the auth_provideR_interface.
Changes the login method to login($username, $password) for
consistency with the providers.
acp() is not fully documented. It appears that it is meant to
return an array of some sort and take in a variable by reference.
PHPBB3-9734
