1. moving/scaling/flipping an item caused a MoveItem action put on the undo stack
2. pressing the mouse button on a flip edge but releasing outside of a flip edge would not clear the flip_active status, leaving the app in a buggy state.
Changed item shape so that it doesn't include handles during multi selection. This gives a more accurate behaviour for getting items out of the rubberband selection (except for the last remaining item, oh well).
There's a slight inaccuracy when getting an already selected item outside of the rubberband: the additional margin of the selection handles needs to be outside of the rubberband too (since it's part of the item's bounding box), making it slightly harder to get an item out of the selection than it should be.
Let's see if it's very noticeable/annoying in practice.
