upload winsize and iters as members to prevent async out of scope issues

cpmpatability

texture channels were not considered correctly, nor was the cuda texture
normalization

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.

* use opaque algorithm interfaces
* add stream support

it caused runtime failures

* it is the only place, where it is used
* no need to make this function public

replaces tabs with spaces