changed tests for tvl1 optflow
correction of a bug preventing compilation with cuda (fmin changed to fminf)

1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions

ECC patch by the author (G. Evangelidis); fixed some OCL Farneback optical flow test failures on Mac

replaces tabs with spaces

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

changed the way the mean value for each pixel is assigned in the output image.

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

modified BackgroundSubtractorMOG2::getBackgroundImage so that it can now work with gray-level images.

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.