NSView boundsRotation

[Fred Kiefer]

I spend some time to find out why the NSView_bounds_scale.m test is 
failing and now I am pretty sure I have the solution, although I don't 
like it.

The problem here is the boundsRotation. Apple seems to have a very 
specific concept here. The value returned by that method (and used 
internally by methods like setBoundsRotation:) isn't what you would 
expect. I think they store this value directly for the NSView and adjust 
it only from the rotation methods. That is, this value has nothing to do 
with the actual rotation value of the current bounds transformation 
matrix, as we implemented it in GNUstep. The important difference is 
when you combine a scale operation with a rotation. Independent of the 
order of these operations Apple comes up with the same rotation value, 
whereas GNUstep will end up with different values.

As there is no use in saying that our results are mathematically 
correct, I suggest that we move over to the Apple way of doing things 
and start storing the rotation in the NSView. This saves us one 
expensive call to atan2() as well.

The same change may also be needed for the frame rotation, but I will 
have to write more test code to verify this.

Fred