v1.4.1: Bugfix for joins in saved query-backed models

SLayer 1.4.1

A bug-fix release for joins on saved query-backed models.

If you save a query as a model and declare joins on it, those joins now work wherever you query that model. Previously they were dropped when the saved model was used, so a filter across one of its joins (say, customers.tier = 'gold' on a saved customer-totals model) was no longer tied to each row and could return a too-large total, such as 150 where the right answer is 120. The joins of the model the saved query reads from are still not inherited; only the joins you declare on the saved model itself apply.

If a query-level model extension repeats a join the base model already has (same target, keys, join type and cardinality - description, meta and key order don't matter), it is now treated as that same join instead of failing as an ambiguous path. An extension join that differs in any of those fields is still a separate join.