Improving ALTER TYPE support

I've been working on a function which returns a setof a composite type. Everytime I've changed the structure of the
returningsetof, I've had to change the type accordingly, which current means doing a drop type ... cascade down to the
function.We should allow one of the following: <br /><br />1) Add a REPLACE on CREATE TYPE (create or replace type)<br
/><br/>2) Allow ALTER TYPE to alter the definition of the type (currently it only allows changes to schema and
ownership)<br/><br />It may get tricky with the first option because there'd be orphaned dependencies on objects which
referencethat particular type while it's being re-created. <br /><br />I'll work on a patch according to feedback.