SampleTrack: fixed non-functional solo and mute buttons

The SampleTrackView did not explicitely have a SampleTrack model
attached and thus trackView::modelChanged() was not called. This way
SampleTrackView's mute and solo buttons were not connected to the
according models of the SampleTrack model. Fix this by calling
setModel() in SampleTrackView::SampleTrackView() (as done in
constructors of other track types too) and overload the
SampleTrackView::modelChanged() method.

Closes #3043836.

include/sample_track.h

@@ -2,7 +2,7 @@
  * sample_track.h - class sampleTrack, a track which provides arrangement of
  *                  samples
  *
- * Copyright (c) 2005-2009 Tobias Doerffel <tobydox/at/users.sourceforge.net>
+ * Copyright (c) 2005-2010 Tobias Doerffel <tobydox/at/users.sourceforge.net>
  *
  * This file is part of Linux MultiMedia Studio - http://lmms.sourceforge.net
  *
@@ -167,6 +167,14 @@ public slots:
 	void showEffects();
 
 
+protected:
+	void modelChanged();
+	virtual QString nodeName() const
+	{
+		return "SampleTrackView";
+	}
+
+
 private:
 	EffectRackView * m_effectRack;
 	QWidget * m_effWindow;