Prepend channel membership prefixes to the nickname in messages

[wasamasa]

It is very easy to overlook the status of a user (chanop, halfop, voiced, ...) as channel membership prefixes are removed from nicknames and only show up in NAMES/WHO/WHOIS output (or implicitly so by observing mode changes). Currently, messages look like this:

<user> hi
*** Mode change: +v user on #channel by admin
<user> thanks for voice
<admin> np
*** Mode change +o admin on #channel by chanserv
<admin> time to fix the /topic

Whereas I'd prefer them to look like this:

<user> hi
*** Mode change: +v user on #channel by admin
<+user> thanks for voice
<admin> np
*** Mode change +o admin on #channel by chanserv
<@admin> time to fix the /topic

This is sort of a prerequisite for implementing multi-prefix as it changes the output of NAMES/WHO/WHOIS to show all applicable channel membership prefixes, rather than just the currently active ones, so it would not be possible to tell who's opped/voiced/etc.

Things to test:

• This should not break nick colors as the prefixes are not part of the nick.

[wasamasa]

Hm, I think I misunderstood multi-prefix as it shows all currently active channel membership prefixes (as opposed to just the highest ranking one). Therefore, to implement this several things are necessary:

• Make sense of the ISUPPORT PREFIX setting
• Parse the initial state from RPL_NAMREPLY
• Keep track of subsequent mode changes in channels and apply them to the users table
• When rejoining the channel, synchronize prefix state again