Adjusted spawn procs for heist and nuke.
Adjusted borer spawns/options/vars.
Added Calamity mode.
Replaces antag intro text and objective announcement with a proc.
Updated borer icons slightly.
Adjustments and a typo fix.
Fixed part of the ninja objective.
Lowercasing some Del() calls.
Merge pull request #5699 from Zuhayr/calamity

Calamity mode.