Support PostgreSQL 10+ partitioning

Include partitioned tables, but ignore their partitions. Without this
change, it would fail on database schemas involving partitioning.

Note the use of the row_to_json() function is to permit backward
compatibility with PostgreSQL 9 and 10. The relispartition column
does not exist until PostgreSQL 10 and the conparentid column does
not exist until PostgreSQL 11. Directly referencing these columns,
while simpler, would cause the query to fail in those earlier
versions. While another approach would be to generate different SQL for
different PostgreSQL versions, that seems like it would be more work.
Note however that this use of JSON means it will no longer work on
PostgreSQL 9.2 and earlier, since the necessary JSON support was
introduced in 9.3

sql.go

@@ -48,7 +48,7 @@ JOIN ONLY pg_namespace n
 ON n.oid = c.relnamespace
 LEFT JOIN pg_description pd ON pd.objoid = c.oid AND pd.objsubid = 0
 WHERE n.nspname = $1
-AND c.relkind = 'r'
+AND c.relkind in ('r','p') AND NOT COALESCE((row_to_json(c)->>'relispartition')::boolean,false)
 ORDER BY c.relname
 `
 
@@ -79,6 +79,7 @@ from (
   where ns.nspname = $1
   and cl.relname = $2
   and con1.contype = 'f'
+  and (coalesce((row_to_json(con1)->>'conparentid'),'0')::oid) = 0
 ) con
 join pg_attribute att
 on att.attrelid = con.confrelid and att.attnum = con.child