Magnetic disturbances in attitude model

# Feature
Related to issue #180 and #193. Satellites can have a residual magnetic dipole resulting in attitude disturbances depending on their orientation to to the Earth magnetic field. Need to addd external torques from the Earth magnetic field to a magnetically charged actor.
## Desired Behavior / Functionality
User defines actor's magnetic charge modelled as a dipole. Attitude model compares the actor dipole orientation with the magnetic field vector of the Earth and provides angular acceleration.
## What Needs to Be Done

1. Model the Earth magnetic dipole at correct offset from the Earth rotational axis at the correct date & time.
2. Find the relative directions of the Earth field and actor dipole vectors
3. Calculate the resulting torque
4. Test the resulting angular acceleration and rotation of the actor

## How Can It Be Tested
Put the actor in a symmetrical state (w.r.t. Earth field lines) and check if it follows the magnetic field lines.