* Proxy#owner has been removed in favor of Proxy#proxy_owner
* @new instance variable renamed to @_new (you shouldn't be using this anyway)
* Removed undefining of object_id in proxies and equal? method in Equality. This means checking equal? for a proxy and a regular document will always be false even if proxy refers to same document. Check Proxy#target instead. (ie: root.equal?(item.root.target))
* find no longer takes options as a last argument. It only works with id, multiple ids, array of ids.
* MongoMapper::MongoMapperError is now MongoMapper::Error
* metaclass, meta_eval, meta_def, class_def removed as they were not being used