Branch prep

Switched to modified map for dev work.
Will be changed back before merge.
Added Supermatter explosion preset for drop bomb verb

Handy for testing mapping changes in engineering.
Added yellow and grey checkered floor sprite
A few mapping tweaks

pipes.dm - Coded in cyan pipes to make mapping easier
Space Station 13 areas.dm - Added EVA hallway area (for engineering redesign)
floors.dmi - Added a couple of floor tile variants (hazard stripe on grime floor, and yellow checkered floor)
Added a couple of floor variants