python - be: Allow operators to take different types.

Log Message:
-----------
Allow operators to take different types.

This allows timestamp() - interval(). Clean up PyPgOperate to handle these
operations appropriately against non-PyPgType objects.

Modified Files:
--------------
    be/include/pypg:
        type.h (r1.8 -> r1.9)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/include/pypg/type.h.diff?r1=1.8&r2=1.9)
    be/src/type:
        array.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/array.c.diff?r1=1.2&r2=1.3)
        bitwise.c (r1.5 -> r1.6)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/bitwise.c.diff?r1=1.5&r2=1.6)
        geometric.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/geometric.c.diff?r1=1.2&r2=1.3)
        network.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/network.c.diff?r1=1.2&r2=1.3)
        numeric.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/numeric.c.diff?r1=1.2&r2=1.3)
        object.c (r1.3 -> r1.4)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/object.c.diff?r1=1.3&r2=1.4)
        record.c (r1.3 -> r1.4)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/record.c.diff?r1=1.3&r2=1.4)
        system.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/system.c.diff?r1=1.2&r2=1.3)
        textual.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/textual.c.diff?r1=1.2&r2=1.3)
        timewise.c (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/python/be/src/type/timewise.c.diff?r1=1.2&r2=1.3)