API review: simplify configuration from plasmoids

[Marco Martin]

Hi all,
right now there are two ways to read and write the configuration from 
plasmoids:
* the new way with plasmoid.configuration, that is a 
KDeclarative::ConfigPropertyMap it's possible to read/write with the usual 
javascript object syntax, and is possible to do property binding

* the old way: plasmoid.readConfig() / plasmoid.writeConfig() with the 
configChanged() javascript function that one has to declare to manage changes 
in configuration.

I propose to kill readConfig and writeConfig that are very clunky and is not 
obvious (and not qml at all) how to react to config changes.
Also to kill the activeConfig propertyof plasmoid, that allowed to have 
multiple kconfiggroups in the applet config. feature that as far i know was 
never ever used (and i'm not 100% sure it still even works)

this would also simplify the appletsrc file, since every applet is now saving 
under
[Containments][id][Applets][id][Configuration][General]

and 

[Containments][id][Applets][id][Configuration]

would be used instead.

(i would argue that if you need a very complex config save, the plasmoid is 
missing the point of simplicity and should rather be an application)

Comments?

-- 
Marco Martin