Modify planet objects to be biaxial ellipsoids

Planets can be represented by biaxial ellipsoids to account for polar flattening. Planet objects should be modified when the planet name changes in the GUI and this is done in the `onChangePlanet` method in the `Ikuchi` class. The object `oPlanetObject` in the `Ikuchi` class can just have it's transformation adjusted so that there is a scaling in the z direction.

Start in the Ikuchi class and inspect the onChangePlanet method and its oPlanetObject transformation. Adjust the z-axis scaling when the planet name changes in the GUI, then verify that each selected planet is displayed as a biaxial ellipsoid with the expected polar flattening.

Written by the indexing model from the issue text.