InstrumentTrack: added support for changing pitch range

Added a new LCD spinbox which allows to control the range of the pitch
knob. This way it's possible to extend the range of the pitch knob up
to 24 semitones in each direction.

include/instrument_track.h

@@ -202,6 +202,7 @@ protected:
 protected slots:
 	void updateBaseNote( void );
 	void updatePitch( void );
+	void updatePitchRange( void );
 
 
 private:
@@ -219,6 +220,7 @@ private:
 	floatModel m_volumeModel;
 	floatModel m_panningModel;
 	floatModel m_pitchModel;
+	intModel m_pitchRangeModel;
 	intModel m_effectChannelModel;
 
 
@@ -379,6 +381,7 @@ private:
 	knob * m_volumeKnob;
 	knob * m_panningKnob;
 	knob * m_pitchKnob;
+	lcdSpinBox * m_pitchRange;
 	lcdSpinBox * m_effectChannelNumber;
 	QPushButton * m_saveSettingsBtn;