Fix assorted bugs in privileges-for-types patch.

Commit 729205571e added privileges on data
types, but there were a number of oversights.  The implementation of
default privileges for types missed a few places, and pg_dump was
utterly innocent of the whole concept.  Per bug #7741 from Nathan Alden,
and subsequent wider investigation.

doc/src/sgml/catalogs.sgml

@@ -2587,7 +2587,8 @@
        Type of object this entry is for:
        <literal>r</> = relation (table, view),
        <literal>S</> = sequence,
-       <literal>f</> = function
+       <literal>f</> = function,
+       <literal>T</> = type
       </entry>
      </row>