Bug 2498 - Loudness Normalization always displays LUFS on launch

Problem:
On opening, the units were always LUFS, and the "treat stereo as dual-mono" check box was always available.

Fix:
On opening, adjust the controls which depend on the value of the Normalize choice.

src/effects/Loudness.cpp

@@ -391,7 +391,9 @@ bool EffectLoudness::TransferDataToWindow()
       return false;
    }
 
-   UpdateUI();
+   // adjust controls which depend on mchoice
+   wxCommandEvent dummy;
+   OnChoice(dummy);
    return true;
 }