Test for boundingCircle() in Features.py; New connectedComponent() method in ImageClass.py

Hey,

I have added the test for Features's boundingCircle(), please tell me if I've done anything wrong.
Also, while working on a little problem, I felt the need for a method to extract connected components with a point as a root. I have written it, please review and consider for a merge.
If it's redundant or erroneous, let me know!

Thank you!