Changed parameter order in documentation of findEssentialMat, because threshold and probability were switched.

and fix the compilation for iOS in the same time

Changed statements of type "#if __CUDA_ARCH__ >= 200" to
"#if defined __CUDA_ARCH__ && __CUDA_ARCH__ >= 200" in order to
avoid warnings about __CUDA_ARCH__ being undefined.

Modified sparse pyrlk optical flow to allow input of an image pyramid which thus allows caching of image pyramids on successive calls.
Added unsigned char support for 1, 3, 4 channel images.

so results are numerically equivalent

fixes #5876

fixes #5878

fixes #5863

fixes #5443

fixes #5643

fixes #5689