Update changes.html

Installation/changes.html

@@ -249,6 +249,13 @@ and <code>src/</code> directories).
       models using the third party Eigen library.
     </li>
   </ul>
+  <h3>CGAL and the Boost Graph Library</h3>
+  <ul>
+    <li>
+      Add a helper function <code>CGAL::clear</code> which clears a
+      MutableFaceGraph efficiently and generically.
+    </li>
+  </ul>
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