Convert Monte Carlo Examples down to one notebook

[HankG]

• Notebook should show each of the major representations: Keplerian Sigma, Cartesian Sigma, Keplerian Covariance, Cartesian Covariance, and make a note about mean vs true anomaly
• Notebook should select the type based on another parameter rather than commented out code so that users know that the values in the code are still valid/legitimate.