Refactored util/transforms.py translate, scale and rotate to just return

Refactored translate, scale and return to just return a matrix to be multiplied instead of the matrix multiplication being done in the method

Adapted scenen linear transforms as appropriate

Adapted examples as appropriate (except for ipython notebooks, cannot test those)
I like how we can spend lengthy discussions about small design choices :) 

I'm ok with just rotate in degrees. One proposal for a hybrid solution though: `def rotate(angle, axis, radians=False)` , i.e. use a bool to switch; not much extra code. My main argument for offering a way to express the angle in either way is that `pi` is not available without an import to np or math.