Remove unused function

src/commands/CommandContext.cpp

@@ -24,7 +24,6 @@ messaging from a command back to its invoker.
 #include "CommandContext.h"
 
 #include <map>
-#include <wx/app.h>
 #include <wx/log.h>
 #include <wx/string.h>
 #include <wx/variant.h>
@@ -87,9 +86,6 @@ void CommandContext::Progress( double d ) const
       pOutput->Progress( d );
 }
 
-AudacityApp * CommandContext::GetApp() const
-{  return (AudacityApp *) wxTheApp;}
-
 void CommandContext::StartArray() const
 {
    if( pOutput )

src/commands/CommandContext.h

@@ -15,7 +15,6 @@
 #include "audacity/Types.h"
 
 class AudacityProject;
-class AudacityApp;
 class wxEvent;
 class CommandOutputTargets;
 using CommandParameter = CommandID;
@@ -55,6 +54,5 @@ public:
    const wxEvent *pEvt;
    int index;
    CommandParameter parameter;
-   AudacityApp *GetApp() const;
 };
 #endif