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_sampling_thread.h

@@ -0,0 +1,59 @@
+/* -*- 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_SAMPLING_THREAD_H_
+#define _QWT_SAMPLING_THREAD_H_
+
+#include "qwt_global.h"
+#include <qthread.h>
+
+/*!
+  \brief A thread collecting samples at regular intervals.
+
+  Continuous signals are converted into a discrete signal by
+  collecting samples at regular intervals. A discrete signal
+  can be displayed by a QwtPlotSeriesItem on a QwtPlot widget.
+
+  QwtSamplingThread starts a thread calling periodically sample(),
+  to collect and store ( or emit ) a single sample.
+
+  \sa QwtPlotCurve, QwtPlotSeriesItem
+*/
+class QWT_EXPORT QwtSamplingThread: public QThread
+{
+    Q_OBJECT
+
+public:
+    virtual ~QwtSamplingThread();
+
+    double interval() const;
+    double elapsed() const;
+
+public Q_SLOTS:
+    void setInterval( double interval );
+    void stop();
+
+protected:
+    explicit QwtSamplingThread( QObject *parent = NULL );
+
+    virtual void run();
+
+    /*!
+       Collect a sample
+
+       \param elapsed Time since the thread was started in milliseconds
+     */
+    virtual void sample( double elapsed ) = 0;
+
+private:
+    class PrivateData;
+    PrivateData *d_data;
+};
+
+#endif