TEMPORAL JOINS: Relation does not exists error, talks about a WITH item -> hide internals

[Piiit]

We need to hide internal rewrites, to not confuse the user. From the input there is no WITH clause at all!

A=# select * from (r                                                                                          
join period with (ts,te,ts,te) s on r.b=d) r ;                                                                
ERROR:  relation "r" does not exist                                                                           
LINE 1: select * from (r                                                                                      
                       ^                                                                                      
DETAIL:  There is a WITH item named "r", but it cannot be referenced from this part of the query.             
HINT:  Use WITH RECURSIVE, or re-order the WITH items to remove forward references.                           

Belongs to #55