Defined dynamic class vars in eZURLAliasML

This satisfies IDEs and helps with debugging
Fix EZP-22177: eZPersistentObject::handleRows() adds bogus rows
Merge pull request #734 from jeromegamez/urlaliasml_object_vars

Define dynamic class vars in eZURLAliasML
Merge pull request #863 from jeromegamez/EZP-22177_handleRows

Fix EZP-22177: eZPersistentObject::handleRows() adds bogus rows