pgsql: Add WITH [NO] DATA clause to CREATE TABLE AS, per SQL.

Log Message:
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Add WITH [NO] DATA clause to CREATE TABLE AS, per SQL.

Also, since WITH is now a reserved word, simplify the token merging code to
only deal with WITH_TIME.

by Tom Lane and myself

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        create_table_as.sgml (r1.37 -> r1.38)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_table_as.sgml?r1=1.37&r2=1.38)
    pgsql/src/backend/catalog:
        sql_features.txt (r1.28 -> r1.29)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/catalog/sql_features.txt?r1=1.28&r2=1.29)
    pgsql/src/backend/parser:
        gram.y (r2.630 -> r2.631)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y?r1=2.630&r2=2.631)
        parser.c (r1.74 -> r1.75)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parser.c?r1=1.74&r2=1.75)
    pgsql/src/interfaces/ecpg/preproc:
        parser.c (r1.3 -> r1.4)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/parser.c?r1=1.3&r2=1.4)
        preproc.y (r1.378 -> r1.379)
        (http://anoncvs.postgresql.org/cvsweb.cgi/pgsql/src/interfaces/ecpg/preproc/preproc.y?r1=1.378&r2=1.379)