slightly improve messages in init.sql

Author: funbringer

expected/pg_pathman.out

@@ -1690,7 +1690,7 @@ INSERT INTO messages SELECT g, md5(g::text) FROM generate_series(1, 10) as g;
 INSERT INTO replies SELECT g, g, md5(g::text) FROM generate_series(1, 10) as g;
 SELECT create_range_partitions('messages', 'id', 1, 100, 2);
 WARNING:  Foreign key 'replies_message_id_fkey' references to the relation 'messages'
-ERROR:  Relation 'messages' is referenced from other relations
+ERROR:  Relation "messages" is referenced from other relations
 ALTER TABLE replies DROP CONSTRAINT replies_message_id_fkey;
 SELECT create_range_partitions('messages', 'id', 1, 100, 2);
 NOTICE:  sequence "messages_seq" does not exist, skipping

init.sql

@@ -341,7 +341,7 @@ BEGIN
 	END LOOP;
 
 	IF is_referenced THEN
-		RAISE EXCEPTION 'Relation ''%'' is referenced from other relations', p_relation;
+		RAISE EXCEPTION 'Relation "%" is referenced from other relations', p_relation;
 	END IF;
 
 	RETURN TRUE;
@@ -515,7 +515,7 @@ BEGIN
 	DELETE FROM @extschema@.pathman_config_params WHERE partrel = parent_relid;
 
 	IF conf_num_del = 0 THEN
-		RAISE EXCEPTION 'table % has no partitions', parent_relid::text;
+		RAISE EXCEPTION 'Relation "%" has no partitions', parent_relid::text;
 	END IF;
 
 	FOR v_rec IN (SELECT inhrelid::regclass::text AS tbl