Port to KPluginLoader/KPluginFactory. Most plugins load.

The problematic ones are:
- kdevplatform/plugins/konsole which uses a custom factory to _not_ load the plugin if the konsole part is not available (i.e. kdebase/apps is not installed), according to the apidocs the custom createInstance function should work but it doesn't and I'm sick from porting atm.
- kdevelop/plugins/appwizard which sets some extra dirs, not sure why this one doesn't load, all the new code does is putting some more code into the constructor of the "generated" factory class.

Matthias I'm cc'ing you as you (hopefully) might have an idea how to port these two plugins