Advanced Celestial Sphere

This is a new version of Jeff Bryant's excellent Demonstration, "The Celestial Sphere". I have refactored the code to make it a bit more reusable. I have also added the thousand brightest stars, the celestial equator, the ecliptic and the first point of Aries. This Demonstration also allows highlighting of individual constellations and viewing of constellations by family, for example, the Zodiac.