[ENHANCEMENT] Update run_dynamics_fast to abide by naming rules

[aweinert-MIT]

Relation

The MATLAB mex function, run_dynamics_fast is used by multiple repositories, including em-model-manned-bayes to simulate aircraft trajectories with a 6DOF physics model. The code does not abide by consistent naming rules.

Description

Update the code to abide by the Google C++ Style Guide naming rules

Alternatives

There are various style guides, if the assignee or contributor recommends a different style please comment on the issue and explain why.

Additional

Recommend addressing issue #10 for the use const variables before addressing this issue, as const variables have a different naming convention.

While the contributing guidelines does not define a style guide for C++, we currently recommend the Google C++ Style Guide for this issue.