SaveTool: add ToastQueue.

Might be useful for warnings and non-fatal errors, to replace standard
SDL message boxes.

src/SaveTool/SaveTool.h

@@ -34,6 +34,7 @@
 
 #include "../ProfileManager/ProfileManager.h"
 #include "../MassManager/MassManager.h"
+#include "../ToastQueue/ToastQueue.h"
 
 using namespace Corrade;
 using namespace Magnum;
@@ -161,6 +162,8 @@ class SaveTool: public Platform::Sdl2Application, public efsw::FileWatchListener
         bool _metricsWindow{false};
 #endif
 
+        ToastQueue _queue;
+
         std::thread _thread; // used for threaded operations such as profile manager init or update checking.
 
         UnsignedInt _initEventId;