Added WHDigest and WHLeave plugins.
Updated LocalStorage to properly encode custom objects.
Added -respondWithFormat: method.
Updated WHPlugin for LocalStorage creation.
Wrap all calls to plugins in try-catch handlers to recover after any possible errors.
Updated to return YES if not onwer. We stil respond to the message, but we don't have permission to use it.
Added WHDigest plugin for keeping a digest of messages. Added WHLeave plugin for owner to make the bot leave rooms.