Resolve "Feature: Send enpoint for non-terminal using implicit NTA"

Closes #36 (closed)

• Categorize changes in Indermediate.jrag
• Update documentation

ragconnect.base/src/main/jastadd/Errors.jrag

@@ -11,6 +11,10 @@ aspect Errors {
     when !getSend() && getEndpointTarget().isTokenEndpointTarget() && token().getNTA()
     to RagConnect.errors();
 
+  EndpointDefinition contributes error("Indexed based list access may only be used for type endpoint targets!")
+    when getIndexBasedListAccess() && !getEndpointTarget().isTypeEndpointTarget()
+    to RagConnect.errors();
+
   // if first mapping is null, then suitableDefaultMapping() == null
   EndpointDefinition contributes error("No suitable default mapping found for type " +
       ((getMappingList().isEmpty())