Qwt 6.0.1 Support

Upgrade to QWT 6.0.1, but still uses a locally patched copy
since support for 8 axes has not been included, despite it
being a relatively simple patch.

Fixes #634.
Fixes #567.

qwt/examples/friedberg/plot.h

@@ -0,0 +1,43 @@
+#ifndef _PLOT_H_
+#define _PLOT_H_
+
+#include <qwt_plot.h>
+#include <qwt_scale_div.h>
+#include <qwt_series_data.h>
+
+class QwtPlotCurve;
+class QwtPlotIntervalCurve;
+
+class Plot: public QwtPlot
+{
+    Q_OBJECT
+
+public:
+    enum Mode
+    {
+        Bars,
+        Tube
+    };
+
+    Plot( QWidget * = NULL );
+
+public Q_SLOTS:
+    void setMode( int );
+    void exportPlot();
+
+private:
+    void insertCurve( const QString &title,
+        const QVector<QPointF> &, const QColor & );
+
+    void insertErrorBars( const QString &title,
+        const QVector<QwtIntervalSample> &,
+        const QColor &color );
+
+
+    QwtScaleDiv yearScaleDiv() const;
+
+    QwtPlotIntervalCurve *d_intervalCurve;
+    QwtPlotCurve *d_curve;
+};
+
+#endif