checkpoint on pass to majorly simplify debug frontend state, and eliminate df entities, and move from cmds -> msgs

src/mdesk/mdesk.c

@@ -211,6 +211,24 @@ md_node_push_tag(MD_Node *parent, MD_Node *node)
   DLLPushBack_NPZ(&md_nil_node, parent->first_tag, parent->last_tag, node, next, prev);
 }
 
+//- rjf: tree building helpers
+
+internal MD_Node *
+md_push_list(Arena *arena)
+{
+  MD_Node *n = md_push_node(arena, MD_NodeKind_List, 0, str8_zero(), str8_zero(), 0);
+  return n;
+}
+
+internal MD_Node *
+md_list_push_ref(Arena *arena, MD_Node *list, MD_Node *ref_dst)
+{
+  MD_Node *ref = md_push_node(arena, MD_NodeKind_Reference, 0, str8_zero(), str8_zero(), 0);
+  ref->first = ref->last = ref_dst;
+  md_node_push_child(list, ref);
+  return ref;
+}
+
 //- rjf: tree introspection
 
 internal MD_Node *