Still needs work; code is messy, and Q is not computed. But I am
getting correct results.
Also need to expand explanations and scenarios.
Need to remove now redundant explanations in EKF chapter, since
they exist in the UKF chapter.
Most of the text is wrong, but changed code to use the
renamed ScaledUnscentedKalmanFilter.
Checking in with bad text because I am in the process of changing
FilterPy to use a class for the sigma points to make it easier
to change the sigma point generation, leaving us with one
UKF class instead of several.
