title: django multiple choice model problems
body: <p>I have two diferents problems with multple choices in models.</p>
  
  <p>The first, i'm trying to do a multiple choice so the user can pick one or more days of the week:</p>
  
  <pre><code>DAYS_CHOICES = (
      (1, _('Monday')),
      ...
      (7, _('Sunday')),
  )
  ...
  day = models.ManyToManyField('day', choices=DAYS_CHOICES)
  </code></pre>
  
  <p>The second problem:</p>
  
  <p>I want to make a ManyToMany Relation with a model define in other model:
  First (Import to the model):</p>
  
  <pre><code>from events.models import Category
  </code></pre>
  
  <p>Second (The field related to the model):</p>
  
  <pre><code>type = models.ManyToManyField('Category', null=True, blank=True)
  </code></pre>
  
  <p>I get this error on syncdb:</p>
  
  <blockquote>
    <p>Error: One or more models did not
    validate: situ.situ: 'day' has an m2m
    relation with model day, which has
    either not been installed or is
    abstract.<br>
    situ.situ: 'type' has an m2m relation
    with model Category, which has either
    not been installed or is abstract.</p>
  </blockquote>