Job fulfillment tweaking [Ready for merge]

Closes #2421 (closed).
Another self imposed goal thrown onto the chip away at pile is to remove V.activeSlave from places where it is not needed, mainly slave gen which should help further removal efforts later on.
This MR:

• Removes V.activeSlave in favor of _slave.
• Removes JFC.reorder and replaces it with a third state for V.JFC.order which is now also documented to an unhealthy degree.
• The widget <<JFCSlave>> which created the slave upon has been replaced by a js function and has thus been moved from src/utility/slaveCreationWidgets.tw to src/pregmod/JobFulfillmentCenter/generateJobFulfillmentSlave.js.
• V.JFC.role is only kept while it is needed.
  
  After this MR, I'll focus on other passages in batches of ten.
  Then eventually work on customSlave at a later date.
  Everything works as expected in extensive testing.
  As a pedantic aside, I do not see the need for $returnTo to be defined for weekly events as the player can only move forward.