Update Initial Conditions and Fix Drag Related Bug

[kylekrol]

Closes #326.
Relates to #325.

Summary of changes

There ended up being a lot of changes made in this PR (mainly for code cleanliness) but I will try and outline the big takeaways here.

• Orbital initial conditions were moved from the ECI to ECEF coordinates frame.This was an issue that wasn't fixed when the orbit propagator was moved to the ECEF frame and caused the simulated orbit to be much more elliptical than it should have been.
• Refactored some of the orbit utility functions to return by value and added more debug information to the orbit and attitude orbit models like altitude and acceleration readouts.
• Other general structural and syntactical improvements.

Testing

The following plots were generated with:

python -m psim -s 8000000 -p truth/orbit_long_duration -ps 10000 -c sensors/base,truth/base,truth/deployment -v SingleOrbitGnc

and notably show monotonically decrasing orbital energy, decaying altitude, and increasing atmospheric density.