RE: Rework subscription-related code for psql and pg_dump

Dear Michael,

Thanks for working on this.
It was not good to follow existing codes without confirmation :-(.

I grepped files in bin/ and could not find lines which includes catalog/pg_xxx.h files.
(One exception is pg_control.h. It is not a catalog-header but has the same prefix.)
The patch basically LGTM.

One comment...
In describeSubscriptions(), only the streaming option is represented as {off, on, parallel},
whereas twophase option is {d, p, e}.
I feel it is bit strange so we can fix to show like {disabled, pending, enabled} by the same approach.
Thought?

Best regards,
Hayato Kuroda
FUJITSU LIMITED