Title: filter roleplay messages
Summary: Ability to filter to only see roleplay messages
Details: Right now, we can only filter for "messages", which includes both roleplays and letters. The two really have nothing to do with each other... I would be nice to filter to only see roleplay messages, making it easier to keep track of them and participate in them, than having to skim through a ton of letters to see them. Equally, when I'm looking for letters, roleplays are of little interest. Splitting that filter in two would be ideal.
Benefits: A more user-friendly message filter system.
Possible Exploits: None
