pgsql-server: Added SET DESCRIPTOR command.

Log Message:
-----------
Added SET DESCRIPTOR command.
    Note that this still has some bugs. The functionality is there though, it's just a matter of fixing the bugs now.
Cleaned up error handling in preprocessor.

Modified Files:
--------------
    pgsql-server/src/interfaces/ecpg/ecpglib:
        descriptor.c (r1.7 -> r1.8)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/ecpglib/descriptor.c.diff?r1=1.7&r2=1.8)
        execute.c (r1.34 -> r1.35)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/ecpglib/execute.c.diff?r1=1.34&r2=1.35)
        extern.h (r1.8 -> r1.9)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/ecpglib/extern.h.diff?r1=1.8&r2=1.9)
    pgsql-server/src/interfaces/ecpg/include:
        ecpglib.h (r1.60 -> r1.61)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/include/ecpglib.h.diff?r1=1.60&r2=1.61)
    pgsql-server/src/interfaces/ecpg/preproc:
        descriptor.c (r1.19 -> r1.20)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/descriptor.c.diff?r1=1.19&r2=1.20)
        extern.h (r1.60 -> r1.61)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/extern.h.diff?r1=1.60&r2=1.61)
        pgc.l (r1.128 -> r1.129)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/pgc.l.diff?r1=1.128&r2=1.129)
        preproc.y (r1.289 -> r1.290)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/preproc.y.diff?r1=1.289&r2=1.290)
        type.c (r1.62 -> r1.63)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/type.c.diff?r1=1.62&r2=1.63)
        variable.c (r1.34 -> r1.35)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/preproc/variable.c.diff?r1=1.34&r2=1.35)

Added Files:
-----------
    pgsql-server/src/interfaces/ecpg/test:
        test_desc.pgc (r1.1)

(http://developer.postgresql.org/cvsweb.cgi/pgsql-server/src/interfaces/ecpg/test/test_desc.pgc?rev=1.1&content-type=text/x-cvsweb-markup)