A handle drag in Edit Points ignored the modifier keys: the point kept
the type it had. In PowerPoint, Shift, Ctrl or Alt held during the drag
sets the point's type.
Shift held while dragging a point's handle now makes it a smooth point.
Ctrl (Cmd on the Mac) makes it a straight point, and Alt (Option) makes
it a corner point. The handle drag passes that type to shape.moveHandle,
and the point keeps it for the next drag without a modifier, as after
Smooth Point, Straight Point or Corner Point in the right-click menu.