pgsql: Add support for temporary views, including documentation and

Log Message:
-----------
Add support for temporary views, including documentation and regression
tests. Contributed by Koju Iijima, review from Neil Conway, Gavin Sherry
and Tom Lane.

Also, fix error in description of WITH CHECK OPTION clause in the CREATE
VIEW reference page: it should be "CASCADED", not "CASCADE".

Modified Files:
--------------
    pgsql/doc/src/sgml/ref:
        create_table.sgml (r1.91 -> r1.92)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_table.sgml.diff?r1=1.91&r2=1.92)
        create_view.sgml (r1.29 -> r1.30)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/doc/src/sgml/ref/create_view.sgml.diff?r1=1.29&r2=1.30)
    pgsql/src/backend/commands:
        view.c (r1.86 -> r1.87)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/commands/view.c.diff?r1=1.86&r2=1.87)
    pgsql/src/backend/parser:
        gram.y (r2.482 -> r2.483)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/backend/parser/gram.y.diff?r1=2.482&r2=2.483)
    pgsql/src/include/commands:
        view.h (r1.21 -> r1.22)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/include/commands/view.h.diff?r1=1.21&r2=1.22)
    pgsql/src/test/regress/expected:
        create_view.out (r1.8 -> r1.9)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/expected/create_view.out.diff?r1=1.8&r2=1.9)
    pgsql/src/test/regress/sql:
        create_view.sql (r1.5 -> r1.6)
        (http://developer.postgresql.org/cvsweb.cgi/pgsql/src/test/regress/sql/create_view.sql.diff?r1=1.5&r2=1.6)