CyclomaticComplexity calculation incorrect when faced with CFG with multiple exit points

[fstarnaud]

For example, the CC of this CFG currently calculates to 1 (e =10, n = 11, components = 1) in features/graph.py: (e - n + 2 * components)
However, if this CFG was normalized to have a single exit point, its value would be 6, which is the value we would expect.