Add reference to the DDJ article discussing a similar algorithm.

Doc/lib/libdifflib.tex

@@ -58,6 +58,15 @@
 \end{classdesc}
 
 
+\begin{seealso}
+  \seetitle{Pattern Matching: The Gestalt Approach}{Discussion of a
+            similar algorithm by John W. Ratcliff and D. E. Metzener.
+            This was published in
+            \citetitle[http://www.ddj.com/]{Dr. Dobb's Journal} in
+            July, 1988.}
+\end{seealso}
+
+
 \subsection{SequenceMatcher Objects \label{sequence-matcher}}
 
 \begin{classdesc}{SequenceMatcher}{\optional{isjunk\optional{,