Avoid making lists comprehensions in vf2 algorithm.
Avoid making lists comprehensions in vf2 algorithm.

Haven't actually run speed tests, but inspecting the C code
that is generated when you cythonize these two versions,
I think this will be faster.

I also think it's a bit simpler to read.
nyee/RMG-Py,chatelak/RMG-Py,pierrelb/RMG-Py,chatelak/RMG-Py,nickvandewiele/RMG-Py,nickvandewiele/RMG-Py,pierrelb/RMG-Py,nyee/RMG-Py