Support ZNC buffextras

[haarp]

Buffextras is a ZNC module that adds additional events to the playback, such as joins/parts/nick changes/kicks/mode changes, etc. These events appear to come from the user *buffextras.

Those currently don't look very nice in HoloIRC. They could be modified to look "native" instead.

A reference implemention for handling them can be found in Hexchat's plugin: https://github.com/knitori/tools/blob/master/hexchat/buffextras.py :)

[poxip]

Hmm..I use znc, and everything works fine..

[haarp]

Not always, it seems. See screenshot

[nadalle]

Fwiw, this is the #1 thing I need. Perhaps some sort of simple plugin system would be a good approach though.

In this case all that's really needed is some sort of glorified regexp replacement mapping. There are lots of other cases people might want this e.g. some bots.