Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::handle() should be compatible with
Action::handle()"
Ref. #190
Includes some minor changes to other things as well, such as the session
token input element now having the same 'name' attribute as everyone else.
(it still retains a 'token-'+noticeid 'id' attribute for clientside JS)
lib/plugin.php now has a parent onAutoload function that finds most common
files that are used in plugins (actions, dataobjects, forms, libs etc.) if
they are put in the standardised directories ('actions', 'classes', 'forms',
'lib' and perhaps some others in the future).
