[refactor] remove homography binary

[carlodef]

This PR replaces the homography c++ program with the Python affine_crop function.

homography was used only with affine transforms so even if the affine_crop function cannot be used to apply generic homographies to images it is enough for the usecase of s2p.

This opens the way to a reduction of the disk read/write as the tiles rectified with affine_crop could be passed in memory (as numpy arrays) to the stereo matching function. This will be done in a future pull request.