"Earth" (or relevant Home planet) preset in planner gives nonsensical results

[Capkirk123]

For whatever reason, when hitting the "Earth" button in the RA planner, the min and max ranges are set to -2918860 km and 301 Gm, respectively. This is very unhelpful and probably unintended, as neither of these values seem to correspond to anything useful?

Migrated from DRVeyl#99

[DRVeyl]

Fix the code at https://github.com/DRVeyl/RealAntennas/blob/master/src/RealAntennasProject/PlannerGUI.cs#L301-L309 to deal with selecting the HomeWorld? Or since that might look strange, carve it out at https://github.com/DRVeyl/RealAntennas/blob/master/src/RealAntennasProject/PlannerGUI.cs#L147 instead