Merge pull request #31 from delorayn1/master

Added UCAC3_guide - a short step-by-step guide how to make astrometry.net index files from UCAC3 catalog
try to install util/py
Merge branch 'master' of github.com:dstndstn/astrometry.net
horizons: add command-line args
Merge pull request #1 from dstndstn/master

merging main fork