Tweaks and fixes

• Add/Edit rebate. Recent changes to allow fine tuning GST on rebate had some very rough edges in UX which causes problems with inputting numbers. Dramatically improved. These improvements will also affect a number of other screens (job item sublets, finance settlement, unit on road cost screens)
• Sel Transaction screen tweaks
  • Change duedate sort to also sort by txn date
  • Rename 'create date' to 'txn date'. Create date implies when txn was inputted into c9 when we explicitly mean the txn date
• Cassons Magician check : use c9 repo cache for this info from now on
• Dealership units : make the deal / quote buttons down buttom work as filters