title: models.py getting huge, what is the best way to break it up?
body: <p>Directions from my supervisor:
  "I want to avoid putting any logic in the <code>models.py</code>.  From here on out, let's use that as only classes for accessing the database, and keep all logic in external classes that use the models classes, or wrap them."</p>
  
  <p>I feel like this is the wrong way to go. I feel that keeping logic out of the models just to keep the file small is a bad idea. If the logic is best in the model, that's where it really should go regardless of file size.</p>
  
  <p>So is there a simple way to just use includes? In PHP-speak, I'd like to propose to the supervisor that we just have <code>models.py</code> include() the model classes from other places. Conceptually, this would allow the models to have all the logic we want, yet keep file size down via increasing the number of files (which leads to less revision control problems like conflicts, etc.).</p>
  
  <p>So, is there a simple way to remove model classes from the models.py file, but still have the models work with all of the Django tools? Or, is there a completely different yet elegant solution to the general problem of a "large" models.py file? Any input would be appreciated.</p>