The phpbb_user object might be used for language variables. Pass it as a
function argument to prepare_form_acp() instead of using globals.
PHPBB3-10018
Pass the phpbb_user object to function get_custom_html(). This object is
used in that method. Also fixed incorrect arguments to get_custom_html()
in phpbb_get_avatar().
PHPBB3-10018
Remove the $request property from the phpbb_avatar_driver class and rather
pass it as function argument if it's needed in a function. Currently this
is only the case for the class methods prepare_form() and process_form().
PHPBB3-10018
This shouldn't be done in the avatar drivers. We need to force the
display all avatar drivers in the ACP or it won't be possible to enable
avatars after they have been disabled.
PHPBB3-10018
Previously the driver class added a variable that defined wether an avatar
driver would return custom HTML. The existence of this variable was
implied in the interface. It's also not needed which is why it has been
removed.
PHPBB3-10018
The addition of "core_" that was used until now would require additional
avatar drivers (e.g. in extensions) to also include that in their class
name which would be incorrect.
PHPBB3-10018
