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_compat.h

@@ -0,0 +1,42 @@
+/* -*- 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_COMPAT_H_
+#define _QWT_COMPAT_H_
+
+#include "qwt_global.h"
+#include "qwt_interval.h"
+#include "qwt_point_3d.h"
+#include <qlist.h>
+#include <qvector.h>
+#include <qpoint.h>
+#include <qsize.h>
+#include <qrect.h>
+#include <qpolygon.h>
+
+// A couple of definition for Qwt5 compatibility
+
+#define qwtMax qMax
+#define qwtMin qMin
+#define qwtAbs qAbs
+#define qwtRound qRound
+
+#define QwtArray QVector
+
+typedef QList<double> QwtValueList;
+typedef QPointF QwtDoublePoint;
+typedef QSizeF QwtDoubleSize;
+typedef QRectF QwtDoubleRect;
+
+typedef QPolygon QwtPolygon;
+typedef QPolygonF QwtPolygonF;
+typedef QwtInterval QwtDoubleInterval;
+typedef QwtPoint3D QwtDoublePoint3D;
+
+#endif