DMs are broken if user changes nick

[kdkasad]

If the user changes their nick using the /NICK command, the nick variable never gets updated. But kirc uses this nick value to check if a message was a message sent directly to the user's nick.

To reproduce:

1. Log on to an IRC server
2. Send yourself a DM (@<nick> test message). This should work as expected.
3. Change your nick (/NICK <nick2>)
4. Send yourself a DM to this new nick (@<nick2> test message).

The message from step 4 will not be highlighted in cyan as a DM should be. Instead, it'll have your nick (i.e. <nick2>) in brackets as if it was a channel name.

[stefan11111]

Does this still happen?
I tested this and it works here.