Watsyn: use fast sinc instead of medium quality (not much diff in this case), increase oversampling to 32 because why not

Graph: optimize graph widget codepaths so that we don't send redundant samplesChanged signals, which in watsyn cause recalculation of the wavetable

include/graph.h

@@ -150,7 +150,7 @@ public slots:
 
 	void setLength( int _size );
 
-	void setSampleAt( int _samplePos, float _value );
+	void setSampleAt( int x, float val );
 	void setSamples( const float * _value );
 
 	void setWaveToSine();
@@ -172,6 +172,7 @@ signals:
 	void rangeChanged();
 
 private:
+	void drawSampleAt( int x, float val );
 
 	QVector<float> m_samples;
 	float m_minValue;