Fix rapid scene switches by random tab

Wait scene was not set while waiting for scene changes on the random
tab.
If wait scene was ever set by other means (sequence) the scene switcher
would immediately wake up as the wait scene is not the expected value.

src/headers/switcher-data-structs.hpp

@@ -192,6 +192,7 @@ struct SwitcherData {
 	void Start();
 	void Stop();
 
+	void setWaitScene();
 	bool sceneChangedDuringWait();
 
 	bool prioFuncsValid();