remove old back-compatibility code

src/ui/header.tis

@@ -144,7 +144,7 @@ class Header: Reactor.Component {
                 <div .separator />
                 {keyboard_enabled ? <li #lock-screen>{translate('Insert Lock')}</li> : ""}
                 {keyboard_enabled && pi.platform == "Windows" ? <li #block-input>{translate("Block user input")}</li> : ""}
-                {handler.support_refresh() ? <li #refresh>{translate('Refresh')}</li> : ""}
+                <li #refresh>{translate('Refresh')}</li>
             </menu>
         </popup>;
     }

src/ui/remote.rs

@@ -197,7 +197,6 @@ impl sciter::EventHandler for Handler {
         fn save_image_quality(String);
         fn save_custom_image_quality(i32, i32);
         fn refresh_video();
-        fn support_refresh();
         fn get_toggle_option(String);
         fn toggle_option(String);
         fn get_remember();
@@ -403,10 +402,6 @@ impl Handler {
         self.send(Data::Message(LoginConfigHandler::refresh()));
     }
 
-    fn support_refresh(&self) -> bool {
-        self.lc.read().unwrap().support_refresh
-    }
-
     fn save_custom_image_quality(&mut self, bitrate: i32, quantizer: i32) {
         let msg = self
             .lc