Fix PreciousStones plugin setup
Thoroughness upgrade: now adds (1..amount) bonus items instead of 2 x amount
A little extra care in inventory GUI to ensure events are always cancelled
If code in a listener class throws an exception, we don't want that to allow players to remove potentially valuable items from the GUI because the event didn't get cancelled.
Same try/finally as before but for inventory drags
Made EjectorUpgrade and DirectionalItemRouterModule implement Directional
Means a method change for these classes
Added new DirectionGadget class
Common gadget for directional item router modules and ejector machine upgrade, (which both implement the Directional interface)