Added heat radiation to H/E pipes

Added black-body heat radiation to H/E pipes placed over /turf/space
according to Stephan-Botzmann law

Conflicts:
	code/ATMOSPHERICS/he_pipes.dm
Merge branch 'master' of https://github.com/ZomgPonies/Paradise
Quick fix to TEG

When one of TEG circulator intakes had gas while the other had no (null)
the air in the first used to be deleted. Fixed this behavior.