Sorotraj

Summary

1. Completely refactored trajectory interpolation to split interpolation of each trajectory segment into separate interpolator functions. This fixes all of the issues with undefined behavior when interpolating.
- Note: The deprecated `as_list` argument has been removed from `Interpolator.get_traj_function()`.
2. Added several checks to ensure trajectory definitions are designed correctly before trying to parse them.
3. Split out useful small function into "utils.py".
4. Added docstrings to every function

Summary

1. Added testing suite using (pytest)[https://docs.pytest.org/]
2. Updated references to deprecated `numpy.matrix` class to `numpy.array`.
3. Performed various houskeeping things (moved all reference links to microrobotics lab rather than Clark's personal github)