fixed slow down in getRectSubPix (original patch by Markus JR Mueller); removed some unused variables and functions

Python typdef fixed. Reverted the example to MOG2. Not time to make the command line switch for now.

1. decrease branch number in CL code by replacing them into weights
2. decrease local mem pressure in reduce operation by using private variables
3. decrease image sampler pressure by caching data into local memory
4. remove unnecessary sync point on the HOST side.

Fixed an issue with weight assignment causing the resulting GMM weights to be unsorted in BackgroundSubtractorMOG2

fix for cv::LUT and cv::transpose