client: Actually implement increment_nick
client: Actually implement increment_nick

I must have missed it before...

Instead of the traditional "x" -> "x|2" -> "x|3" -> ...,
we go "x" -> "x|N" -> "x|NN" -> ...
where N is a random digit 0-9.
This means log(n) nick change attempts to find an unused nick instead of n,
while still (mostly) keeping nick lengths to a minimum.

ekimekim/girc