AUP3: Removes OD code related to project file handling

This removes all of the OnDemand code embedded throughout
    the main codebase. Individual files related specifically
    to OD have been left in place, but removed from the build.

src/UndoManager.h

@@ -51,7 +51,6 @@
 
 #include <vector>
 #include <wx/event.h> // to declare custom event types
-#include "ondemand/ODTaskThread.h"
 #include "ClientData.h"
 #include "SelectedRegion.h"
 
@@ -168,11 +167,6 @@ class AUDACITY_DLL_API UndoManager final
 
    // void Debug(); // currently unused
 
-   ///to mark as unsaved changes without changing the state/tracks.
-   void SetODChangesFlag();
-   bool HasODChangesFlag() const;
-   void ResetODChangesFlag();
-
  private:
    AudacityProject &mProject;
  
@@ -185,10 +179,6 @@ class AUDACITY_DLL_API UndoManager final
 
    SpaceArray space;
    unsigned long long mClipboardSpaceUsage {};
-
-   bool mODChanges;
-   mutable ODLock mODChangesMutex;//mODChanges is accessed from many threads.
-
 };
 
 #endif