Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::prepare() should be compatible with
Action::prepare(array $args = Array)
Ref. #190
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).
