Handling of SAL Work "Interruption" resource Refund

[Sn1p3rr3c0n]

Assume a SAL is Tasked to build explosive Shells on a Machining Table.
The Bill targets the production till n Shells are in a specific zone.

They are moved there on a Belt. (Items on Belts currently are not counted see: #729 )
The Items will then reach the Zone at a delayed Point causing the current bill to be interrupted.
This refunds the materials, and might place some of them on the output belt

We might want to check how to best place those resource back or handle the event differently