pep8 unittest_application and unittest_formfields

[rset] Always complete attribute/relation caches in ResultSet.get_entity RQL queries are often designed to fill up the ORM's caches when fetching entities out of the result set. Until now, if an entry already existed in the entity cache, ResultSet.get_entity would return it unchanged, not using the new ResultSet's contents to update the attribute cache, breaking expectations (if the attributes are needed, they'd then be fetched later one at a time, one entity at a time), resulting in loads of DB accesses. So we change ResultSet.get_entity so that: * if the entity is already cached and has been instantiated from the same rset, it is returned as-is (to avoid loops) * if the entity is not yet cached, it is instantiated * if the entity is cached via another rset, its attribute/relation caches are completed Closes #9942503

[rset] refactoring of _build_entity method define a method for entity instantiation and storage in cache (related to #9942503)