Fixes handle()-related strict warnings such as "Strict Standards:
Declaration of AdminPanelAction::handle() should be compatible with
Action::handle()"
Ref. #190
I implemented changes from quitter.se's new API that their front-end qvitter
uses, https://github.com/hannesmannerheim/qvitter/blob/master/api-changes-1.1.1/CHANGES
However I left out the URL shortening commens, since I believe whatever behaviour
they experienced that caused them to implement this was a bug (or many) and should
be fixed in their proper areas and that shortening should not be entirely left
out in API calls.
