* Follow-up of [17630]:
  - Finish implementation of expression cache keys, including BT support.
  - Really deprecate portal type filtering.
* Filter expressions shall use 'context' to refer to the object. All other
  variables (here, container, isDelivery, etc) are deprecated.
  Remove now useless expression context cache.
* Compute the list of objects to catalog only once per filter expression.

Optimisations will be really effective when erp5_mysql_innodb is updated.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@32324 20353a03-c40f-0410-a6d1-a30d3c3de9de