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_arrow_button.h

@@ -0,0 +1,52 @@
+/* -*- 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_ARROW_BUTTON_H
+#define QWT_ARROW_BUTTON_H
+
+#include "qwt_global.h"
+#include <qpushbutton.h>
+
+/*!
+  \brief Arrow Button
+
+  A push button with one or more filled triangles on its front.
+  An Arrow button can have 1 to 3 arrows in a row, pointing
+  up, down, left or right.
+*/
+class QWT_EXPORT QwtArrowButton : public QPushButton
+{
+public:
+    explicit QwtArrowButton ( int num, Qt::ArrowType, QWidget *parent = NULL );
+    virtual ~QwtArrowButton();
+
+    Qt::ArrowType arrowType() const;
+    int num() const;
+
+    virtual QSize sizeHint() const;
+    virtual QSize minimumSizeHint() const;
+
+protected:
+    virtual void paintEvent( QPaintEvent *event );
+
+    virtual void drawButtonLabel( QPainter * );
+    virtual void drawArrow( QPainter *,
+        const QRect &, Qt::ArrowType ) const;
+    virtual QRect labelRect() const;
+    virtual QSize arrowSize( Qt::ArrowType,
+        const QSize &boundingSize ) const;
+
+    virtual void keyPressEvent( QKeyEvent * );
+
+private:
+    class PrivateData;
+    PrivateData *d_data;
+};
+
+#endif