Rename isCUDA into isApplyOnImage

WindowFeature::isCUDA has been renamed into WindowFeature::isApplyOnImage

By default calling ImageWindowIterator::apply runs WindowFeature::apply on chunks.
Due to lack of performances when dealing with CUDA code, a WindowFeature::apply on image has to be designed.
Rename WindowFeature::apply into WindowFeature::applyOnChunk
Add new WindowFeature methods to cppimagewindowiterator.pyx