Update 42c: Swarm moved to "Experimental" classes + bugfixes

Changes:
- moved Swarm to the "Experimental" class pack
- reduced Happy and Grumpy gun damage from 20 to 16

Fixed:
- can no longer spawn as Swarm mid-round
- fixed Swarm drones sometimes becoming bugged out after being destroyed, resulting in them breaking the cycling of alive Swarm drones and not being repairable
- fixed NPCs sometimes trying to pathfind through closed doors

Level Editor:
- fixed "Custom Stealable Object" missing mesh bug introduced in the last update
- added additional client-side logging for loading "Custom Stealable Objects"
- fixed "Garbage Bin" object not working correctly