remove commented out code, more comments

core/models.py

@@ -23,6 +23,12 @@ from django.template import Context, loader
 
 import troggle.core.models_survex 
 
+"""This file declares TroggleModel which inherits from django.db.models.Model 
+All TroggleModel subclasses inherit persistence in the django relational database. This is known as
+the django Object Relkational Mapping (ORM).
+There are more subclasses define in models_caves.py models_survex.py etc.
+"""
+
 def get_process_memory():
     usage=resource.getrusage(resource.RUSAGE_SELF)
     return usage[2]/1024.0