title: Mongoengine Document as EmbeddedDocument
body: <p>I have a mongoengine.Document subclass User defined.</p>
  
  <pre><code>class User(Document):
      meta = {'collection': 'users', 'allow_inheritance': False}
      _id = ObjectIdField()
      password = StringField(max_length=50)
      name = StringField(max_length=50, required
  </code></pre>
  
  <p>now i want to use it as standalone document with its own collection but i want also to use it as EmbeddedDocument as part of Game record:</p>
  
  <pre><code>class Game(Document):
      meta = {'collection': 'games', 'allow_inheritance': False}
      _id = ObjectIdField()
      name = StringField()
      owner = EmbeddedField(User)
  </code></pre>
  
  <p>but there is a problem. Mongoengine allows to embed only EmbeddedDocument subclasses. Is there a way to solve it? </p>