pgsql: Fixed error handling in numeric conversion (Joachim).

Log Message:
-----------
Fixed error handling in numeric conversion (Joachim).
Further regression cleanup.

Modified Files:
--------------
    pgsql/src/interfaces/ecpg:
        ChangeLog (r1.319 -> r1.320)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/ChangeLog.diff?r1=1.319&r2=1.320)
    pgsql/src/interfaces/ecpg/include:
        pgtypes_numeric.h (r1.15 -> r1.16)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/include/pgtypes_numeric.h.diff?r1=1.15&r2=1.16)
    pgsql/src/interfaces/ecpg/pgtypeslib:
        numeric.c (r1.28 -> r1.29)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/pgtypeslib/numeric.c.diff?r1=1.28&r2=1.29)
    pgsql/src/interfaces/ecpg/test/expected:
        pgtypeslib-num_test2.c (r1.1 -> r1.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/pgtypeslib-num_test2.c.diff?r1=1.1&r2=1.2)
        pgtypeslib-num_test2.stdout (r1.1 -> r1.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/expected/pgtypeslib-num_test2.stdout.diff?r1=1.1&r2=1.2)
    pgsql/src/interfaces/ecpg/test/pgtypeslib:
        num_test2.pgc (r1.1 -> r1.2)

(http://developer.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/test/pgtypeslib/num_test2.pgc.diff?r1=1.1&r2=1.2)