WaveTrack::WaveTrackDisplay does not encode scale or spectral selection...

... SpectrogramSettings does that instead, and Preferences or View Settings
are the user interface for changing it.

Handle invalidation of spectrogram pixel cache for scale type changes,
just as for other changes of settings.  No more
TrackArtist::InvalidateSpectrumCache().

View type of track now switches to Spectrum when applying or OKing the
View Settings... dialog and the Spectrogram page is open (and for now
it is still the only page)

src/AudacityApp.cpp

@@ -93,6 +93,7 @@ It handles initialization and termination by subclassing wxApp.
 #include "commands/Keyboard.h"
 #include "widgets/ErrorDialog.h"
 #include "prefs/DirectoriesPrefs.h"
+#include "prefs/SpectrogramSettings.h"
 
 //temporarilly commented out till it is added to all projects
 //#include "Profiler.h"
@@ -1011,7 +1012,11 @@ void AudacityApp::InitLang( const wxString & lang )
    //
    // This must go _after_ creating the wxLocale instance because
    // creating the wxLocale instance sets the application-wide locale.
+
    Internat::Init();
+
+   // Some static arrays unconnected with any project want to be informed of language changes.
+   SpectrogramSettings::InvalidateNames();
 }
 
 void AudacityApp::OnFatalException()