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)
Can we make it so that `rotate(x)` raises an error, and users *must* write explicitely either `rotate(degrees=x)` or `rotate(degrees=y)`? Whatever default we choose, it will always confuse part of our users...