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_legend.h

@@ -0,0 +1,117 @@
+/* -*- 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_LEGEND_H
+#define QWT_LEGEND_H
+
+#include "qwt_global.h"
+#include "qwt_abstract_legend.h"
+#include <qvariant.h>
+
+class QScrollBar;
+
+/*!
+  \brief The legend widget
+
+  The QwtLegend widget is a tabular arrangement of legend items. Legend
+  items might be any type of widget, but in general they will be
+  a QwtLegendLabel.
+
+  \sa QwtLegendLabel, QwtPlotItem, QwtPlot
+*/
+
+class QWT_EXPORT QwtLegend : public QwtAbstractLegend
+{
+    Q_OBJECT
+
+public:
+    explicit QwtLegend( QWidget *parent = NULL );
+    virtual ~QwtLegend();
+
+    void setMaxColumns( uint numColums );
+    uint maxColumns() const;
+
+    void setDefaultItemMode( QwtLegendData::Mode );
+    QwtLegendData::Mode defaultItemMode() const;
+
+    QWidget *contentsWidget();
+    const QWidget *contentsWidget() const;
+
+    QWidget *legendWidget( const QVariant &  ) const;
+    QList<QWidget *> legendWidgets( const QVariant & ) const;
+
+    QVariant itemInfo( const QWidget * ) const;
+
+    virtual bool eventFilter( QObject *, QEvent * );
+
+    virtual QSize sizeHint() const;
+    virtual int heightForWidth( int width ) const;
+
+    QScrollBar *horizontalScrollBar() const;
+    QScrollBar *verticalScrollBar() const;
+
+    virtual void renderLegend( QPainter *,
+        const QRectF &, bool fillBackground ) const;
+
+    virtual void renderItem( QPainter *,
+        const QWidget *, const QRectF &, bool fillBackground ) const;
+
+    virtual bool isEmpty() const;
+    virtual int scrollExtent( Qt::Orientation ) const;
+
+Q_SIGNALS:
+    /*!
+      A signal which is emitted when the user has clicked on
+      a legend label, which is in QwtLegendData::Clickable mode.
+
+      \param itemInfo Info for the item item of the
+                      selected legend item
+      \param index Index of the legend label in the list of widgets
+                   that are associated with the plot item
+
+      \note clicks are disabled as default
+      \sa setDefaultItemMode(), defaultItemMode(), QwtPlot::itemToInfo()
+     */
+    void clicked( const QVariant &itemInfo, int index );
+
+    /*!
+      A signal which is emitted when the user has clicked on
+      a legend label, which is in QwtLegendData::Checkable mode
+
+      \param itemInfo Info for the item of the
+                      selected legend label
+      \param index Index of the legend label in the list of widgets
+                   that are associated with the plot item
+      \param on True when the legend label is checked
+
+      \note clicks are disabled as default
+      \sa setDefaultItemMode(), defaultItemMode(), QwtPlot::itemToInfo()
+     */
+    void checked( const QVariant &itemInfo, bool on, int index );
+
+public Q_SLOTS:
+    virtual void updateLegend( const QVariant &,
+        const QList<QwtLegendData> & );
+
+protected Q_SLOTS:
+    void itemClicked();
+    void itemChecked( bool );
+
+protected:
+    virtual QWidget *createWidget( const QwtLegendData & ) const;
+    virtual void updateWidget( QWidget *widget, const QwtLegendData & );
+
+private:
+    void updateTabOrder();
+
+    class PrivateData;
+    PrivateData *d_data;
+};
+
+#endif