SaVi satellite constellation visualizer savi-dev

Adding commentary on source of mu value - there are different sources.

Putting geomview changes inside ui freeze in tianquin.

Fixing local copy of svn to honour cvs Id tags - again.

Updating dead surrey.ac.uk urls to live lloydwood.sourceforge.net ones.

Adding Tianqin gavity wave-sensing constellation.

Updating dialogs to match minor changes in SaVi 1.6.

We lose the titlebars as these vary between systems.
At some point all images will need updating together.

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.