Don't update the model unnecessarily when scaling or scrolling

[svenefftinge]

Atm the underlying component model is recreated on every vie change. Which causes a lot of objects being created and garbage collected.
We should instead use the viewport and scaling information on an existing component model.
Separated from that the component model should only be recreated if a new data model is available.

[svenefftinge]

I played around a bit with the using scale and position on the pixiJS stage object. And it works nicely. Also it cleans up the code as we no longer need to translate between logical units and viewable pixels.

Here is a snapshot with the prototype state:

[jbicker]

This is already done for states.
For elements which can't be scaled (because we have to preserve line thickness) we need to update the coordinates without removing and creating component objects.