Improved usability & code cleaning:
- Support for blanket orders, in addition of purchase tenders
("Purchase Agreements")
- Create a RfQ in one click, no wizard anymore
- Control of quantities really purchased
- Better control of side-effects thanks to purchase requisition types
- JS code removed (not necessary)
- Workflow removed
Closes#11666
- Preserved explicit 3rd-party copyright notices
- Explicit boilerplate should not be necessary - copyright law applies
automatically in all countries thanks to Berne Convention + WTO rules,
and a reference to the applicable license is clear enough.