add const keyword to some methods
outsource translating coordinates of triangles into a function
replace algorithm to calculate the intermediate fade point with a more failsafe version
fix a bug in the intermediate fade triangle render code
squash and simplify function to find cross-intersection again
shorten and make intermediate fade triangle render code more performant
Merge remote-tracking branch '_origin/lights' into lights

Conflicts:
	src/landscape/fow/C4FoWLight.cpp
	src/landscape/fow/C4FoWLight.h
make Peter's change conform to the naming scheme