Sync version number to 2.5-pre
Fix Search persistence.
Add Base#attributes_for_dirty
Don't remove object state when deleted.
Don't delete twice the same object
Rewrite sequel/session_spec. ALL specs pass.
Remove obsolote functions.
Tidy up Persistor.
Update doc.
Add PersistableTrait.
Add parents to PersistorTrait.
Add children to PersistableTrait.
Add PersistAssociationTrait
Add association_class
Fix new_attribute_for for non Resource attributes.
Misc optimisation on persistor traits.
Fix parent key for compound class name.
add parents in persistable trait.
Clean persistor.
Implement deletable_parents for persistable trait.