add optin to delete saved license info

src/Menu.hh

@@ -32,6 +32,7 @@ namespace MainMenuItemID {
   constexpr uint32_t PATCHES            = 0x11666611;
   constexpr uint32_t PROGRAMS           = 0x11777711;
   constexpr uint32_t DISCONNECT         = 0x11888811;
+  constexpr uint32_t CLEAR_LICENSE      = 0x11999911;
 }
 
 namespace InformationMenuItemID {

src/ReceiveCommands.cc

@@ -789,6 +789,11 @@ void process_menu_selection(shared_ptr<ServerState> s, shared_ptr<Client> c,
           c->should_disconnect = true;
           break;
 
+        case MainMenuItemID::CLEAR_LICENSE:
+          send_command(c, 0x9A, 0x04);
+          c->should_disconnect = true;
+          break;
+
         default:
           send_message_box(c, u"Incorrect menu item ID.");
           break;

src/ServerState.cc

@@ -347,6 +347,8 @@ void ServerState::create_menus(shared_ptr<const JSONObject> config_json) {
   }
   this->main_menu.emplace_back(MainMenuItemID::DISCONNECT, u"Disconnect",
       u"Disconnect", 0);
+  this->main_menu.emplace_back(MainMenuItemID::CLEAR_LICENSE, u"Clear license",
+      u"Disconnect with an\ninvalid license error\nso you can enter a\ndifferent serial\nnumber, access key,\nor password", 0);
 
   try {
     this->welcome_message = decode_sjis(d.at("WelcomeMessage")->as_string());