fix unnecessary field-name/model-name conflicts (i.e. field_name == model_name.lower() )

=> __init__ + __getattribute__ now handle only the Django inheritance
references that are needed ('modela_ptr', 'modelc' etc.), avoiding
unnecessary conflicts with field names.

.gitignore

@@ -5,6 +5,7 @@
 .project
 .pydevproject
 .settings
+nbproject
 
 tmp
 libraries-local