SaVi satellite constellation visualizer savi-dev

Removed warning about using 1.9 or later, since we'll be on 1.9.5
forevermore.

Finally mentioning 1.6 in COPYRIGHT.

Updating TLE dialog, now that we say Download
and give a shout out to Celestrak.

Updating constants screenshot to reflect updated
constants dialog, with easier-to-understand
rotation period.

We're now into development for 1.6.1.

Minor documentation spacing.

Download is clearer terminology.

saying "Download" is better.

Updating zlib version example.

Removing redundancy.