- Added addoninfo.txt

Map 1:
- Added infected nav block for the fire barrier
- Fixed a secret weapon spawn not pickupable

Map 2:
- Fixed a broken ladder on a truck
- Fixed infected getting stuck under the gravepile's ramps

Map 3:
- Fixed a hole on the wall at the start of the sewer
- End saferoom weapon now spawn Tier 2

Map 4:
- Added a trigger to disable saferoom's nav mark (prevent witch from getting confused)

Map 5:
- Fixed missing ambient sounds
- Swans now floats