Added the option start without building key (since it has been requested many times)

Added the option to exclude burns and glass shards injuries to limbs

-Added the option to start with in building already infested with zombies, useful when starting in hospital or large completely empty buildings.
The amount of zombies spawned is based on the Sandbox Population value and the total number of rooms in the building (more rooms=more zeds)
-Optimized fires placement

The algorithm for placing fires has been modified and optimized

Updated fires placement

Initial release