SaVi satellite constellation visualizer savi-dev

Details tweaks - default text is now always visible, at the bottom,
Recreating the window is inelegant, but a simple way to prevent a
crash if launching then immediate Empty Space... -- and it does
draw attention to the information.

Noting geosynchronous in scripts for repeating groundtracks.
Could make this its own submenu - undecided about that.

Adding first attempts at Singh's efficient four-satellite systems
as described in Nature Communications.

Minor Draim tweaks.

If we launch SaVi and immediately Empty space, freeze. Fixing that, inelegantly.
Problem with the Details window content.

Minor tweaks to Draim comments.

Minor tweaks to Karousel script for clarity.

Fixing comment hashes.

using dx.doi.org for consistency.

Minor tweaks to help intro text to give scripts location.