Qt5 built in qwt (#570)

- qt4->qt5
- in built qt5 6.1.5 because rhel7 is not upto date with qt5, removed findqwt.cmake
- made a fix in qwt lib (qwt_plot_layout.h) to work with 5.15 and lower versions for qrect constr.
- qt5 forms fixed, qt4 many hard coding forms switched to forms including qtabwidget, scrolls etc, fonts moved to forms
 - docking option enabled by default, removed option to disable docking feature from "Mode"
- added qVersionResolve utility functions to handle compatibility before and after qt5.12
- qtplots (ian's code) takes in gain mode enable to set some settings within the class, with proper gain plot ticks
- ensure gain plots have no zooming of z axis in 2d and y axis in 1d
- removed placeholder text in qpalette in main window form as its not supportd until 5.12 (so using qt5.9 designer insted of qt5.15 to cope)
- tab order
Servers:
- fixed some error messages that were empty for fail in funcs (mostly minor as if this error, major issues)

libs/qwt-6.1.5/include/qwt_abstract_legend.h

@@ -0,0 +1,71 @@
+/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
+ * Qwt Widget Library
+ * Copyright (C) 1997   Josef Wilgen
+ * Copyright (C) 2002   Uwe Rathmann
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the Qwt License, Version 1.0
+ *****************************************************************************/
+
+#ifndef QWT_ABSTRACT_LEGEND_H
+#define QWT_ABSTRACT_LEGEND_H
+
+#include "qwt_global.h"
+#include "qwt_legend_data.h"
+#include <qframe.h>
+#include <qlist.h>
+
+class QVariant;
+
+/*!
+  \brief Abstract base class for legend widgets
+
+  Legends, that need to be under control of the QwtPlot layout system
+  need to be derived from QwtAbstractLegend.
+
+  \note Other type of legends can be implemented by connecting to
+        the QwtPlot::legendDataChanged() signal. But as these legends
+        are unknown to the plot layout system the layout code
+        ( on screen and for QwtPlotRenderer ) need to be organized
+        in application code.
+
+  \sa QwtLegend
+ */
+class QWT_EXPORT QwtAbstractLegend : public QFrame
+{
+    Q_OBJECT
+
+public:
+    explicit QwtAbstractLegend( QWidget *parent = NULL );
+    virtual ~QwtAbstractLegend();
+
+    /*!
+      Render the legend into a given rectangle.
+
+      \param painter Painter
+      \param rect Bounding rectangle
+      \param fillBackground When true, fill rect with the widget background
+
+      \sa renderLegend() is used by QwtPlotRenderer
+    */
+    virtual void renderLegend( QPainter *painter,
+        const QRectF &rect, bool fillBackground ) const = 0;
+
+    //! \return True, when no plot item is inserted
+    virtual bool isEmpty() const = 0;
+
+    virtual int scrollExtent( Qt::Orientation ) const;
+
+public Q_SLOTS:
+
+    /*!
+      \brief Update the entries for a plot item
+
+      \param itemInfo Info about an item
+      \param data List of legend entry attributes for the  item
+     */
+    virtual void updateLegend( const QVariant &itemInfo,
+        const QList<QwtLegendData> &data ) = 0;
+};
+
+#endif