changed how fire works

-fire switched to release energy by burning fuel and generating heat from that
- reorganzied the fire process in a saner manner
changed variable settings for the change in fire.dm

added one new variable
deleted three variables that are no longer used
readjusted composition of syndie bombs

set them to produce a 1-2-5 explosion for the fire changes
Merge pull request #3246 from LordBraindead/bleeding-edge-freeze

rewrite of fire code - second attempt