Removed unnecessary float->double conversions
Removed unnecessary int->float conversions
Move subtraction to improve parallelism
Only negate the coordinates once
Move 2 additions outside the loop
Merge remote-tracking branch 'upstream/master' into c++optimizations

Conflicts:
	ref/rays.cpp
Check the number of cores instead of making 512 threads
Merge remote-tracking branch 'm42a/c++optimizations'

Conflicts:
	ref/rays.cpp
go back to int
ignore crays