eval: distinguish irtree 'parents' from 'overrides' - parents are any irtree which some other expression is extending, and overrides are a subset of those, being just the irtrees overridden by auto-hooks. doing this because when we unwind the parent chain, sometimes we do not want to do that for basic expression extensions - we just want to undo the overrides.

src/eval_visualization/eval_visualization_core.c

@@ -101,6 +101,10 @@ ev_expansion_type_from_key(E_TypeKey type_key)
         done = 1;
         result = key;
       }
+      else
+      {
+        done = 0;
+      }
     }
     
     //- rjf: if we have meta-expression tags in the type chain, defer