Safe Spot Fixes, Empty Ammo Sound, & More Main Menu UI

1. Fixed safe spots in Hangar B (swarm mode)
2. Fixed a safe spot in Flooding (swarm mode)
3. Fixed a map escape spot on Industrial (swarm mode)
4. Added empty ammo sound when trying to shoot with 0 ammo
5. Added "EXP multiplier" to player stats on main menu
6. Added text to notify player about guns past lvl 60 requiring DLC purchase (if not purchased)