Fix mAng3_c copy assignment, clean up list node templates

include/f/f_list_nd.h

@@ -28,10 +28,31 @@ public:
     fBase_c *p_owner;
 };
 
-class fLiNdBaAutoUnlink_c  : public fLiNdBa_c {
+// TODO unofficial, move these to a more appropriate place
+class fLiNdBaAutoUnlink_c : public fLiNdBa_c {
 public:
     fLiNdBaAutoUnlink_c(fBase_c *owner) : fLiNdBa_c(owner) {}
-    ~fLiNdBaAutoUnlink_c() { unlink(); }
+    ~fLiNdBaAutoUnlink_c() {
+        unlink();
+    }
+};
+
+template <typename T>
+class dAcRef_c : fLiNdBaAutoUnlink_c {
+public:
+    dAcRef_c(T *owner) : fLiNdBaAutoUnlink_c(owner) {}
+    dAcRef_c() : fLiNdBaAutoUnlink_c(nullptr) {}
+    ~dAcRef_c() {}
+
+    void link(T *ref) {
+        p_owner = ref;
+    }
+    void unlink() {
+        fLiNdBa_c::unlink();
+    }
+    T *get() {
+        return static_cast<T *>(p_owner);
+    }
 };
 
 #endif