Snapping when grabbing

[kathwill]

As a presentation creator, I want to arrange my morphs when I grab them with a chosen snap size (similiar to resizing the morphs) in order to be able to apply my preferred snap size consistently.

• When snapping is enabled and I grab a morph, I should only be able to drop the morph in the "grid" (that is given by the snap size)

Estimated effort: