Editing v2, Cleanup

* Implemented alternative flows for dragging & dropping; rows cannot be
dropped on places where they are not supported (for example its no
longer possible to drag 1/2 1/2 in sidebar). Same applies for copy
pasting; its not possible to paste a menu item in a regular page for
example. Also for swapping the system checks if the swapping is allowed.
* Cleaned up commented code that was deprecated
* Renamed getpagerowtemplates to getpostrowtemplates