Correctly save position of callouts.

This patch only works for shapes that are not rotated/skewed. This fixes
the most occurences of the bug 289646 -  callouts have different position after load save

@Jan: could you please have a look at the transformed shapes. There is some transformation magic that
I still have a hard time to master.

CCBUG: 289646
CCMAIL: jaham@gmx.net