[gnc] PySim Drag is Incorrect

[divijgarg]

We discovered that PySim's drag model for x is too high, causing us to underapproximate our altitude. When removing the drag force, we end up overapproximating altitude. This may be due to relative velocity currently being defined as the vehicle's velocity, rather than subtracting out wind conditions.
Branch: dg/pysim

[AhmedKhan04]

Added a adaptive wind model. Seems like much better but still not good results. Issue could also come from other sources such as incorrect Q matrix.

[AhmedKhan04]

With the Adaptive wind model this is the best results we are yet to see...