Add wxList::AsVector<>() helper.

This can be useful in legacy code using wxList to progressively replace it
with wxVector.

See #14814.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@73003 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

interface/wx/list.h

@@ -391,6 +391,13 @@ public:
         Returns the size of the list.
     */
     size_type size() const;
+
+    /**
+        Returns a wxVector holding the list elements.
+
+        @since 2.9.5
+    */
+    wxVector<T> AsVector() const;
 };