Build 3.0-R4

Changes
- Emergencies with separate buildings attached to them can no longer cause flash-over of another building
- General Back-end code Stability updates
- Further reduced Plane sounds
- Changed some of the footstep sounds
- New footstep sounds can be turned down with the general effects audio slider
- Reduced amount of planes in sky


Bug Fixes
- Plane sound still not being affected by audio slider
- Fixed issues with Axe, and doors