Add small moon orbital data from SPICE kernels

[theradioboy]

I just learned that Cartes du Ciel uses Spice kernels for proper computation of the position of small satellites of Jupiter and Saturn. See for instance this discussion: https://groups.io/g/skychart/topic/himalia_and_other_faint_moons/87269173

Would it be possible to include this kind of feature?

[gzotti]

Sure.