include current message in message history

[raedah]

Using the up arrow to go through the message history will overwrite a message you are currently typing with no way to return to it. After using the up arrow, the behavior I expect is to use the down arrow to return to the current message I was working on.

[jrick]

irssi does the same so i'm ok with this change.

In fact irssi will let you arbitrarily add entries to your "up history" for lack of a better term. if you type something, up, and type again, both of them will appear in your "up history".

[marcopeereboom]

That is a pile of work. I'll take a diff.

I want it too :)