Silently added more filters

I've added two more filters. The first one is a "match all" filter, which just matches all messages. Very handy if you want to apply filters on all messages to cleanup your inbox or doing other repeating stuff.This will become even more useful, when the "automatically apply filter on new messages" option is added on a per-folder basis. This way, you can apply filters on newly added messages. This is something many people want. Just drop a message into a folder, execute the filter and process the message data.The other filter checks if the sender already exists in your addressbook. This is currently used in the spam filter anyway, to achieve an automatic whitelisting.