i,j,k,l indices on Out of Plane Angles

[coltonbh]

First a huge thanks for providing these projects for us to work through--enormously helpful!

Also, just spent a few hours debugging my code and realized the issue may be with your indices on the out-of-plane angle exercise. You can see the solution code here. I believe this does not match with the out-of-angle formula provided in the README.md which describes k as the central index from which e_ki is computed. In the code the slight swapping of k and j in the out-of-plane code loop makes j the central atom and changes the computed angles.

Am I missing something here? Thanks so much :)