pgsnap - pgsnap: Add "useless indexes" report (from an idea of Josh

Log Message:
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Add "useless indexes" report (from an idea of Josh Berkus,
http://it.toolbox.com/blogs/database-soup/finding-useless-indexes-28796).

Modified Files:
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    pgsnap/pgsnap:
        ChangeLog (r1.75 -> r1.76)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnap/pgsnap/pgsnap/ChangeLog.diff?r1=1.75&r2=1.76)
    pgsnap/pgsnap/lib:
        navigate.php (r1.28 -> r1.29)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnap/pgsnap/pgsnap/lib/navigate.php.diff?r1=1.28&r2=1.29)
        reports.php (r1.9 -> r1.10)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnap/pgsnap/pgsnap/lib/reports.php.diff?r1=1.9&r2=1.10)

Added Files:
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    pgsnap/pgsnap/lib:
        uselessindexes.php (r1.1)

(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pgsnap/pgsnap/pgsnap/lib/uselessindexes.php?rev=1.1&content-type=text/x-cvsweb-markup)