pg_dump dumps event triggers and transforms unconditionally

I noticed $subject while trying to fix the extension membership problem
Karsten Hilbert complained of last week.  I do not think that if I ask
for a dump of a single table, that should include event triggers.

AFAICT event triggers don't belong to any particular schema, so I'd
propose that they be dumped only when include_everything is true,
which is the usual rule for objects that don't belong to any schema.

Transforms have got the same issue, which means that the dump of a
database containing, eg, hstore_plperl is outright broken: it will
dump both the extension *and* a CREATE TRANSFORM command.  Again, they
ought to obey the default rules for schema-less objects, which in
this case is "dump if include_everything and not an extension member".
        regards, tom lane