Revert commit 57b6b5df02.
Revert commit 57b6b5df02.

This commit breaks isTargetedMessage() in the case where
command.prefix is not defined (is null), the message is
sent to the channel, but the bot's nick nor aliases appear
in the message.  This should be FALSE, but isTargetedMessage()
returns TRUE because command.prefix is null.

phergie/phergie,shocm/phergie,shocm/phergie