Fix data transformation for simple subtypes of list/dict structures

The scalar values of generic list/dist structures were not transformed
according to _subtype transformation rules (to be precise, the
transformed value was not saved).

Author: ipspace

netsim/data/validate.py

@@ -560,7 +560,7 @@ def validate_item(
               attributes=attributes,
               enabled_modules=enabled_modules)
 
-  return True
+  return OK
 
 """
 validate_attributes -- validate object attributes