Data Module Update 1: Tests + Minor Features

[tristandijkstra]

This pull requests introduces the first significant update to the data module (Horizons, MPC, SBDB). The following changes have been made:

Features

• Implementation of the JPL Horizons Ephemeris API
• New feature to retrieve interpolated observation data (RA/DEC) using the JPL Horizons Ephemeris API
• A wrapper has been created that allows for the generation of JPL Horizons Tabulated Ephemeris settings through tudatpy.numerical_simulation.environment_setup.ephemeris
• A wrapper has been created that allows for the generation of central_sbdb gravity model settings using SBDB in tudatpy.numerical_simulation.environment_setup.gravity_field
• another central_sbdb_density model setting allows for gravity field creation based on the sbdb diameter and a user-inputted density.
• Additional paramaters for the SBDB query such as gravitational parameter, diameter and orbit class.
• Exposed add_gravity_field_model in tudatpy.numerical_simulation.environment_setup.
• added option to add central_sbdb to bodies when running .to_tudat() in BatchMPC.

Tests

• Automated test to cover user input for BatchMPC
• Automated test to cover user input for JPL Horizons
• Automated test comparing JPL Cartesian to SPICE ephemeris
• Automated test comparing JPL interpolated RA/DEC data to BatchMPC
• Automated test comparing BatchMPC ObservationCollection retrieved using to_tudat() to the original observation data

Automated tests have a 87% coverage for Horizons and 88% coverage of BatchMPC.

[tristandijkstra]

@DominicDirkx when merged, please add the following two files to the testset:

• tests\test_data_mpc.py
• tests\test_data_horizons.py

[tristandijkstra]

This update is complemented by a small addition in the first MPC example: tudat-team/tudatpy-examples#41