Add SemiAxes parameter for globular clusters

[SevenSpheres]

As @LafuenteAstronomy said in #524, some globular clusters are ellipsoidal.

I meant that they look too circular and not spherical, since though the model is 3D, it isn't fully rendered to the point it actually looks like a sphere. Besides, a few globular clusters don't really look spherical at all, such as Mayall II and Omega Centauri, which look more ellipsoidal (Which makes sense, as both of them are remnants of the galactic cores of dwarf galaxies that were cannibalized by the Andromeda and Milky Way Galaxies respectively), and Palomar 1 and Djorgovski 1, which look too dispersed and therefore, somewhat lacks a proper spherical structure

I'm not sure how globulars look "too circular and not spherical", or how to fix that.

[SevenSpheres]

This could possibly also be added for galaxies:

Irregular galaxies need some way to make them elongated, sort of like E1-6 galaxies in 1.6.1. This applies specifically to galaxies like Wolf-Lundmark-Melotte.

[LukeCEL]

Just saying: we don't know the true dimensions of any globular clusters or elliptical galaxies, since we can only look at them from one direction. All we have is the projected ellipticity parameter, which is defined as (a-b)/a, where a is the longer axis and b is the shorter axis of the ellipse.