Multiple complexity support

[simonrenoult]

trafficstars

Forking #28 to implement my own feedbacks:

• using escomplex (with babel) to prevent reinventing algorithms that exist off the shelf.
• defaulting complexity to 1 if files are not supported given the chosen strategy
• using node-sloc to preserve support among languages

It's still missing unit tests but that should not take a long time.

[henriklippke]

Hello, is there a rough estimate of when the PR will be finished and merged? Thanks a lot Henrik

[simonrenoult]

@henriklippke the PR has been merged, the feature is available in 4.3 :)