pgsql: Adjust parser so that POSTQUEL-style implicit RTEs are stored

Log Message:
-----------
Adjust parser so that POSTQUEL-style implicit RTEs are stored with
inFromCl true, meaning that they will list out as explicit RTEs if they
are in a view or rule.  Update comments about inFromCl to reflect the way
it's now actually used.  Per recent discussion.

Modified Files:
--------------
    pgsql/doc/src/sgml:
        release.sgml (r1.393 -> r1.394)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/release.sgml.diff?r1=1.393&r2=1.394)
    pgsql/src/backend/parser:
        parse_relation.c (r1.115 -> r1.116)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/parse_relation.c.diff?r1=1.115&r2=1.116)
    pgsql/src/include/nodes:
        parsenodes.h (r1.291 -> r1.292)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/nodes/parsenodes.h.diff?r1=1.291&r2=1.292)