Any plan to support unsupervised optical flow

[YangHai-1218]

Hi, thanks for your great work. I am just wondering if you have any plan to support unsupervised optical flow algorithms. There are also many works for unsueprvised optical flow, like uflow. and the performance of these algorithms are impressive considering the unsupervised learning paradigm. So i think it is a good idea to support some unsupervised optical flow algorithms.