Element always on top during dragging
Generic dragging wip
Store initial postion as a property instead of as attributes
Dragging of group wip
We need to count the groups position against their own initial position
not only against the one in the group selected.
Do we need to clone all elements in the group?
create object for draggedObject (WIP)

THis is completely messy, and I have only to commit it because I have
to leave the computer.
make svg->getRoundDiffPos more generic
svg: Improve Point().distanceTo

Now this method uses getRoundDiffPos, so it should be obsolete
to call this at any other place.

Maybe getRoundDiffPos should now be integrated into the Point class?