Reduce overlap on "scroll".

When using the 'down' button on a certain number of lines curently displayed at the bottom of the screen is redisplayed at the top of the screen. Given our usually small screen size and often large pages requiring many 'down' operations the number 'four' seems too generous so lets reduce it to 'two'.

apps/webbrowser/www.c

@@ -525,7 +525,7 @@ PROCESS_THREAD(www_process, ev, data)
 	CTK_WIDGET_FOCUS(&mainwindow, &backbutton);
 #endif /* WWW_CONF_HISTORY_SIZE > 0 */
       } else if(w == (struct ctk_widget *)&downbutton) {
-	firsty = pagey + WWW_CONF_WEBPAGE_HEIGHT - 4;
+	firsty = pagey + WWW_CONF_WEBPAGE_HEIGHT - 2;
 	start_loading();
 	open_url();
 	CTK_WIDGET_FOCUS(&mainwindow, &downbutton);