Speed up production request computation
I've splited the code related to production request from #3516 (closed) to this issue to ease it's review. The code mainly does two things:
* Convert production set_moves (and _set_move_planned_date) into dualmethod
* Save the production requests and create it's moves in a bunch.
I've tested the results on a production database giving the following results:
* Without the patch: 53.964437 seconds
* With the patch: 8.714269 seconds
On both cases 231 productions where generated.