Non-linear 6dof simulation

[real-tintin]

Implement the full (6dof) non-linear model to enable for more complex offline simulation. Some stuff which needs to be done:

• Refactor the attitude estimation, make clear interfaces s.t the estimators can easily be re-used.
• Implement the non-linear model. Should this be a class e.g., NonLinearModel(Estimator, CONSTANTS, ...)?
• Create a GUI to execute and analyze the simulation in e.g., Tkinter.
• Determine values of the non-linear model i.e., drag coefficient.
• Need to be able to add noise e.g., sine or gaussian to estimator input.

[real-tintin]

Done.