Fix causality path bugs
Fix causality path bugs

* Ensure that it is always an array

* Fix ->has_in_path() and use it consistently

* Don't have ->initiate() call ->forward(); use a common
  ->_do_forward() implementation instead

epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp,epfl-idevelop/jahia2wp