Add support for new default help handbook page for non-existent handbooks.

This partially resolves bug report 1839.

kdoctools/tdeio_help.cpp

@@ -111,11 +111,25 @@ TQString HelpProtocol::lookupFile(const TQString &fname,
             redirect = true;
         }
         else
+        {
+            const TQString helpNotFound = "khelpcenter/helpnotfound/index.html";
+            if (!langLookup(helpNotFound).isEmpty())
+            {
+                KURL red;
+                red.setProtocol("help");
+                red.setPath(helpNotFound);
+                red.setQuery(query);
+                redirection(red);
+                kdDebug( 7119 ) << "redirect to " << red.url() << endl;
+                redirect = true;
+            }
+            else
             {
                 unicodeError( i18n("There is no documentation available for %1." ).arg(path) );
                 finished();
                 return TQString::null;
             }
+        }
     } else
         kdDebug( 7119 ) << "result " << result << endl;