The new demo worldmap.cpp generates a PNG image of
a Mercator projection of the Earth, showing color-coded
intensity of sunlight (yellow) and moonlight (blue).
This sample program shows how to efficiently calculate
horizontal altitudes of the Sun and Moon across many
different geographic locations, for a given observation time.
This program demonstrates converting ecliptic coordinates
to horizontal coordinates at a given time for a given observer.
It searches for the two locations on the horizon where the
ecliptic plane intersects it.
This example demonstrates how to calculate equatorial coordinates
and horizontal coordinates of solar system bodies.
Added explanatory comments to moonphase.c.
Added #defines for MIN_YEAR, MAX_YEAR in astronomy.h.
Removed unnecessary code from positions.html; no longer need
to calculate geocentric vector before calculating equatorial coordinates.
