max_nick_length is broken

[DarkRTA]

Hi, I attempted to use this to bridge to an IRC network with a rediculously low nicklen (9 characters), and I ended up having to modify the code as this option does not behave how I expect it to.

A good change would be to have it behave similarly to this:

if we assume the following is true:
nicklen: 9
suffix: |d
Discord Username: IHaveALongName#0001

then we should end up with something like this:

irc nick: IHaveAL|d
irc fallback nick: IH_0001|d

This looks incredibly ugly but with such a short nicklen you can't get any better. This is still way better than the option being broken and the bridge trying to use longer nicknames than what is permitted on the server.