D3128r4: add predecessor/distance function object change to revision history (#127)

Author: pratzl

D3128_Algorithms/tex/revision.tex

@@ -80,4 +80,8 @@ \subsection*{\paperno r4}
                   \item Link Analysis: Jaccard Coefficient.
                   \item Minimum Spanning Tree: Kruskal, Inplace Kruskal, and Prim.
             \end{itemize}
+      \item Replace raw container (range) predecessor and distance parameters with function objects
+            (\tcode{PredecessorFn}, \tcode{DistanceFn}) constrained by new \tcode{predecessor_fn_for} and
+            \tcode{distance_fn_for} concepts, enabling flexible storage strategies for per-vertex properties.
+            Add \tcode{container_value_fn} adaptor and \tcode{_null_predecessor} sentinel for convenience.
 \end{itemize}