WaveTrackView::BuildSubViews can be simplified...

... The setting of scale type now happens in the default constructor of
WaveformSettings, which calls LoadPrefs.

Since creation of WaveformSettings is always forced, we don't need the
distinction between WaveTrack::GetWaveformSettings and
WaveTrack::GetIndependentWaveformSettings.

That distinction was more analogy with the handling of SpectrogramSettings that
we don't need now.

src/commands/SetTrackInfoCommand.cpp

@@ -387,7 +387,7 @@ bool SetTrackVisualsCommand::ApplyInner(const CommandContext & context, Track *
       }
    }
    if( wt && bHasScaleType )
-      wt->GetIndependentWaveformSettings().scaleType = 
+      wt->GetWaveformSettings().scaleType = 
          (mScaleType==kLinear) ? 
             WaveformSettings::stLinear
             : WaveformSettings::stLogarithmic;