title: Django admin interface inlines placement
body: <p>I want to be able to place an inline inbetween two different fields in a fieldset. You can already do this with foreignkeys, I figured that inlining the class I wanted and defining it to get extra forms would do the trick, but apparently I get a:<br>
      "class x" has no ForeignKey to "class y"<br>
  error. Is this not something that is supported in Django 1.0? If so, how would I go about fixing the problem, if there isn't a pre-existing solution? </p>
  
  <p>in models.py  </p>
  
  <pre><code>class Place(models.Model):
      name = models.CharField(max_length=50)
      address = models.CharField(max_length=80)
  
  class Owner(models.Model):
      name = models.CharField(max_length=100)
      place = models.ForeignKey(Place)
      background = models.TextField()
      license_expiration = models.DateTimeField('license expiration')
  </code></pre>
  
  <p>in admin.py</p>
  
  <pre><code>class PlaceInline(admin.TabularInline):  
      model = Place  
      extra = 5  
  
  class OwnerAdmin(admin.ModelAdmin):  
      fieldsets = [  
          (None,    {'fields': ['background','place', 'license_expiration']}),  
      ]  
      inlines = [PlaceInline]  
  </code></pre>