Every Shape operation should return a new shape #69
Description
In frame-per-frame operations involving shapes, it could happen that users want to alter a shape from the original state at every iteration. Some of the current operations modify the shape in place, preventing further re-use. The current workflow involves making a manual copy of the shape and then do the transformation on it, but it's inefficient (and there is no copy method either, so to copy users do Shape(other_shape.drawing_cmds)).
We considered adding a in_place flag to all shapes' operations, but it could lead to undesired side effects and inconsistencies.