Enhancements

[BadPirate]

Several enhancements:

• Sorting: Provide a sort block and messages will be sorted as they are inserted (in optimal binary tree method)
• Gravatars - Set a gravatar email string on a message and the gravatar for that user (or a custom random gravatar) will be set as the icon for the opponent!
• Duplicate message prevention - Off by default, enable to prevent messages with the same sender, content and timestamp from being added
• Filter - Allow for setting a custom predicate filter on messages that will automatically filter out any messages that don't match!