[Gtkradiant] Where to start plugin development?

[namespace]

Hello!

I plan to create some example plugins for radiant. It would help me to get a deeper understanding of the codebase
and would provide a startpoint for new developers, especially for those who just want to add one or two features
for their project but don't know where to start.

My two ideas:
- new xml mapexport plugin
This looks pretty redundant at first since we already have a (unsupported) xml export option, but let me explain :)
The output for this plugin is not intended to be used with q3map2 or any id game:

<brush>
	<polygon nx="" ny="" nz="" material="">
		<vertex x="" y="" z="" />
		<vertex x="" y="" z="" />
		...
	</polygon>
</brush>

The main difference is that the plugin will export convex polygons instead of windings. Since triangulating
convex polygons is a trivial task the output could be used by many intepended programmers who don't want
to write a parser for the quakeformats and mess with windings.
Btw, I would implement this functionality anyway because my project depends on this output but instead of just hacking it
into the excisting xmlplugin I would implement it in a clean plugin. :)

- A custom entityplugin, just to show how to do it.
No idea what could be of use here, suggestions?

Right now the mapplugin is my top priority, if you have other ideas or want to help me please let me know.

namespace