New: Added support for scaling in CPView

This PR adds the support of scaling in CPView.
There are two new public methods in CPView : -(void)scaleUnitSquareToSize: and -(void)setScaleSize:
-(void)scaleUnitSquareToSize: works exactly as in COCOA, it means if you set a first scale to 0.5 and then 0.5 again, the scaleSize of the view will be 0.25
-(void)setScaleSize: works just with the given value. If you set 0.5 after the scaleSize will still be 0.5, even if it was already set to 0.5. This method is definitely better in use, specially when using the scaleSize binding with a slider.
This PR adds a cssStyle attributes in CPCompatibility.j as well.
Previously the behavior of the methods convertRect/convertPoint didn't work like Cocoa, specially when the two views weren't in the same Window. Now it does.

Test app in Tests/Manual/ScalingTest