Remove cv.sfm dependency

[philipqueen]

Closes #4.

I decided to take this on to better understand the math going on in the backend here. I haven't built the sfm version of opencv myself, and don't have the pseye cameras or drones to test my replacement of it myself, so thorough real use testing should be done before merging this.

I did look at the opencv_sfm test suite, but they only test by making raw data, doing one set of conversions, converting back, and testing that the results match. Since I didn't implement the reverse of these functions I didn't implement that, and it did not give me examples to test these functions with.

The file that contained the functions I adapted from included a BSD license that I have included here out of caution.

[jyjblrd]

Hey Philip,

Thanks for the PR! This could be very helpful. Unfortunately I don't have the time/ability to properly test this right now, so I'll pull it into a new branch and update the readme to let people know that the no opencv-sfm code is experimentally available.

The best way to probably test this would be to generate random data and compare the opencv-sfm results to your code, which unfortunately would also require setting up some testing infrastructure which doesn't currently exist in the codebase.

[philipqueen]

Great that sounds good to me!

If I end up figuring out the testing I’ll make another PR into that branch.