Plugin System

[arneboe]

Most chat clients support plugins to extend the user interface in one way or another.

A plugin system could be used to implement the less mainstream features, e.g. the latex support (#121).
Qt provides an easy way to create and load plugins (http://qt-project.org/doc/qt-5/plugins-howto.html).

I think the first question to answer is what could/should be modifiable by a plugin. If that question is answered we could start thinking about the the interfaces that need to be defined to support such plugins.