IPlugin::save_state is never called

[10110111]

I've just to put my state saving code there to discover that it's never called. Grepping the code gave zero mentions it.

[eteran]

probably about time that I implement session files :-) Related bugs:

#36, #2, #3

[eteran]

@10110111, just a heads up that I am considering changing the plugin state API. At the moment, it is based on a QByteArray, but I think it may be better to use QVariantMap. This will make it simpler to store the results in human readable formats if desired.

Any objections?

[10110111]

This is a good thing I think. And I'm currently not using state API since it doesn't work, so it shouldn't conflict if you change it.