Light refactor of __repr__() for readability
Add 1d and 3d test points
Improve logic in slope() for horizontally colocated points
Add known slopes for known 3d points
Modify slope logic to correctly compute slope

Now, the adjacent side is the horizontal distance between both points, whereas
the opposite side is the vertical distance between both points.

Thank God for triangles.
Complete VERY basic flight protocols based on point navigation