Manage Free Slots

Converts the nearly useless List Free Slots command to Manage Free Slots

From here you can painlessly add and remove job slots to your hearts content because the HoP is Dead/Shit/AFK/In Hiding and everyone is rolling assistant because there's nothing else left.

It can't be used before round start to make rounds with only clowns because of jobs.txt being applied at round start. Alas.