* Generally changes the BasicProposalItemListModel's sort to take the
  BasicProposalItem::order member into account.
* Currently only the QML completion and quick fixes set the order.
* This means the 'Apply signature changes' quick fix is now further up
  than the 'add definition' quick fix.

Change-Id: I7b5bc82aa37fca232fddd630ab3273437e1bcc09
Reviewed-by: Leandro Melo <leandro.melo@nokia.com>