v1.6 Lepton Epoch

Windows binaries included, courtesy of pyinstaller.

This release includes great improvements both to the physics solvers, orbit mathematics and visualization tools.

Notable changes since last release:

• Yoshida8 physics solver implemented.
• Proximity zones and basic vessel-vessel collisions implemented.
• Timed command execution implemented.
• Auto-export of plot data to csv files implemented.
• Astrometry data to initial state conversion utility added.
• Keplerian (2 body) orbit projector partially rewritten and improved.
• Camera movement by command line commands implemented.
• Coordinate system grid visualization implemented.
• New scenarios and improvements to old ones.