Location of spools#649

Because of the climate, I store filament in sealed containers, 4 spools per container. I assign spools to containers, but it’s not a permanent assignment, if I take a spool out and put it into the AMS or a printer, another spool takes its place in the container. the problem is that the removed spool, the one going to the AMS, still keeps its old Location assignment, and after a while it turns into a total mess for me. maybe it would be worth adding an optional setting (for people who want it :D) where assigning a spool to a printer or a slot automatically clears its saved Location?
also, it would be nice if choosing a location during Unassign was optional instead of mandatory

Done! Live in a day or two :)