edje: Add support for map zoom to use other part center.
In edc, zoom is supposed to happen from object center, there is no way to
change the center of the zoom.
Adding support to change the center of zooming just like map rotation by using
other part's center.
Reviewers: cedric, zmike
Reviewed By: zmike
Differential Revision: https://phab.enlightenment.org/D9115