xyz = moon(time)
return position XYZ of the moon relative to center of earth
at TIME; the XYZ has leading dimension 3; x is along the vernal
equinox, z is ecliptic north. The corrections to the lunar orbit
are from Schlyter (see sch_moon). Claimed accurate to 2 arc minutes
over some reasonable time. TIME is in days since 0/Jan/00 (that is,
0000 UT 31/Dec/99). This is 1.5 days earlier than the J2000 epoch.
interpreted function, defined at i/kepler.i line 261