orafce - orafce: Fix bugs reported by tushar.

Log Message:
-----------
Fix bugs reported by tushar.
- Fix crash in plvsubst.string()
- Add to_date(datestr)

Modified Files:
--------------
    orafce:
        Makefile (r1.28 -> r1.29)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/Makefile.diff?r1=1.28&r2=1.29)
        alert.c (r1.16 -> r1.17)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/alert.c.diff?r1=1.16&r2=1.17)
        orafunc.sql.in (r1.50 -> r1.51)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/orafunc.sql.in.diff?r1=1.50&r2=1.51)
        pipe.c (r1.24 -> r1.25)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/pipe.c.diff?r1=1.24&r2=1.25)
        plvdate.c (r1.11 -> r1.12)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/plvdate.c.diff?r1=1.11&r2=1.12)
        plvstr.c (r1.16 -> r1.17)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/plvstr.c.diff?r1=1.16&r2=1.17)
        plvsubst.c (r1.7 -> r1.8)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/plvsubst.c.diff?r1=1.7&r2=1.8)
        shmmc.c (r1.13 -> r1.14)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/shmmc.c.diff?r1=1.13&r2=1.14)
        uninstall_orafunc.sql (r1.2 -> r1.3)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/uninstall_orafunc.sql.diff?r1=1.2&r2=1.3)
    orafce/expected:
        orafunc.out (r1.19 -> r1.20)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/expected/orafunc.out.diff?r1=1.19&r2=1.20)
    orafce/sql:
        orafunc.sql (r1.17 -> r1.18)
        (http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/orafce/orafce/sql/orafunc.sql.diff?r1=1.17&r2=1.18)