Updated slide transition:
* Can work with "toHide==null" or "toShow==null"
* Resets position of moved object after animation
* Final position of "toShow" object is its original position (where it is located when before animation is started)
Update fade transition:
* Can now work with toHide==null or toShow==null
Ensure in "fade" tansition, that cb is not called twice
Updated scale transition:
* Can deal with "toHide==null" and "toShow==null"
* Reset position and scale of toHide after transition
* Final position and scale is given by the objects original position and scale (when transition is started)
added transitions to Options widget