[PATCH] Explicit shell types

Hi,

The only thing I considered wrong with the previous patch was it's odd
behaviour w.r.t. creation of types with the same name as one in
pg_catalog. However, Tom said this is not a serious issue given the
same problem exists in many other places in PostgreSQL.

So, I've added some regression tests and here is the patch for
inclusion.

Have a nice day,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> Patent. n. Genius is 5% inspiration and 95% perspiration. A patent is a
> tool for doing 5% of the work and then sitting around waiting for someone
> else to do the other 95% so you can sue them.