SlicerLeapMotionControl in Slicer 4.11.0

Thanks for reporting the problem.

Since Slicer was recently updated to use with Python 3 (see [1] for more details), extensions and more general any example of code also need to be updated to support python 3 and it seems the SlicerLeapMotionControl scripts still need to be updated to support it.

[1] Updating slicer to work with python 3