Issue #2540 : Python bindings for various "detectMultiScale()"
Added Haar cascade for russian cars licence plate detection, 16 stages cascade, pretty fast.
Fixed pyopencv_to w/FLANN IndexParams in python3.

The keys() and values() functions on dictionaries in Python 3 no longer
return lists.  pyopencv_to() for flann::IndexParams now iterates over
the dictionary in a way that is version-agnostic.
Merge pull request #2782 from HapeMask:py3_flann
Merge pull request #2777 from alexstadnik:master
Merge pull request #2773 from abidrahmank:pycascade
Added support for 3-channels, changed CCOEFF
changed CCOEFF cn==1