[CR] Adds firetruck spawns

Fixes http://smf.cataclysmdda.com/index.php?topic=4628.0 .

This adds firetruck spawn chances to the Office/Hotel Towers (large, heavily populated civilian structure that required evacuation in the Cata) and Schools (evac the kids), and fire/police spawn chances under the Specials section of the parking lot.

First time I've messed with actual *map-editing* and I'm not at all sure about the Tower spawns (vehicle dimensions, etc).  If folks more knowledgeable could check me up and let me know whether I'm smushing anything, I'd appreciate it.  I don't think the firetrucks are that much larger than flatbeds, but still.  Thanks for your time/consideration.