[TASK] Use jQuery UI's "sortable" in page module

Port the code to use jQuery UI's "sortable" instead of draggable and
droppable, which solves some issues:

- The element position is stored after dropping it, solving the
"hang" effect.
- In "Languages" view, the elements are now properly movable. Moving
the elements between languages, which is error prone, is now not
possible anymore (it was possible before, but it was not saved).

Resolves: #65311
Releases: master
Change-Id: I5af23e258e057eb8c855760bc2ad5fa6989e6686
Reviewed-on: http://review.typo3.org/37262


Reviewed-by: Christian Kuhn <lolli@schwarzbu.ch>
Tested-by: Christian Kuhn <lolli@schwarzbu.ch>
Reviewed-by: Benjamin Mack <benni@typo3.org>
Tested-by: Benjamin Mack <benni@typo3.org>