[Development] Settings API for QML

[Bache-Wiig Jens]

> 
> To get the discussion going, here's my suggestion for that API:
> PersistentSettings
> {
>    property bool loadOnStartup: true
>    property bool saveOnExit: true
>    function load()
>    function save()
> }

I would also consider an even simpler API. How about we introduce a new keyword for persistent properties and make it part of the language.

Rectangle {
    id: root
    persistent property width: 400
    persistent property height: 300
}

What this means is that the application will automatically store its persistent properties on exit and recall those properties on startup. By default they would be initialised to the bound value.  
It will need some attached properties or other meta data to override default storage locations etc. And we also need to enforce id's to keep values unique per qml file. 

Jens