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/doc/man/man3/QwtSamplingThread.3

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+.TH "QwtSamplingThread" 3 "Mon Jun 1 2020" "Version 6.1.5" "Qwt User's Guide" \" -*- nroff -*-
+.ad l
+.nh
+.SH NAME
+QwtSamplingThread \- A thread collecting samples at regular intervals\&.  
+
+.SH SYNOPSIS
+.br
+.PP
+.PP
+\fC#include <qwt_sampling_thread\&.h>\fP
+.PP
+Inherits QThread\&.
+.SS "Public Slots"
+
+.in +1c
+.ti -1c
+.RI "void \fBsetInterval\fP (double \fBinterval\fP)"
+.br
+.ti -1c
+.RI "void \fBstop\fP ()"
+.br
+.in -1c
+.SS "Public Member Functions"
+
+.in +1c
+.ti -1c
+.RI "virtual \fB~QwtSamplingThread\fP ()"
+.br
+.RI "Destructor\&. "
+.ti -1c
+.RI "double \fBinterval\fP () const"
+.br
+.ti -1c
+.RI "double \fBelapsed\fP () const"
+.br
+.in -1c
+.SS "Protected Member Functions"
+
+.in +1c
+.ti -1c
+.RI "\fBQwtSamplingThread\fP (QObject *parent=NULL)"
+.br
+.RI "Constructor\&. "
+.ti -1c
+.RI "virtual void \fBrun\fP ()"
+.br
+.ti -1c
+.RI "virtual void \fBsample\fP (double \fBelapsed\fP)=0"
+.br
+.in -1c
+.SH "Detailed Description"
+.PP 
+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 \fBQwtPlotSeriesItem\fP on a \fBQwtPlot\fP widget\&.
+.PP
+\fBQwtSamplingThread\fP starts a thread calling periodically \fBsample()\fP, to collect and store ( or emit ) a single sample\&.
+.PP
+\fBSee also\fP
+.RS 4
+\fBQwtPlotCurve\fP, \fBQwtPlotSeriesItem\fP 
+.RE
+.PP
+
+.SH "Member Function Documentation"
+.PP 
+.SS "double QwtSamplingThread::elapsed () const"
+
+.PP
+\fBReturns\fP
+.RS 4
+Time (in ms) since the thread was started 
+.RE
+.PP
+\fBSee also\fP
+.RS 4
+QThread::start(), \fBrun()\fP 
+.RE
+.PP
+
+.SS "double QwtSamplingThread::interval () const"
+
+.PP
+\fBReturns\fP
+.RS 4
+Interval (in ms), between 2 calls of \fBsample()\fP 
+.RE
+.PP
+\fBSee also\fP
+.RS 4
+\fBsetInterval()\fP 
+.RE
+.PP
+
+.SS "void QwtSamplingThread::run ()\fC [protected]\fP, \fC [virtual]\fP"
+Loop collecting samples started from QThread::start() 
+.PP
+\fBSee also\fP
+.RS 4
+\fBstop()\fP 
+.RE
+.PP
+
+.SS "virtual void QwtSamplingThread::sample (double elapsed)\fC [protected]\fP, \fC [pure virtual]\fP"
+Collect a sample
+.PP
+\fBParameters\fP
+.RS 4
+\fIelapsed\fP Time since the thread was started in milliseconds 
+.RE
+.PP
+
+.SS "void QwtSamplingThread::setInterval (double interval)\fC [slot]\fP"
+Change the interval (in ms), when \fBsample()\fP is called\&. The default interval is 1000\&.0 ( = 1s )
+.PP
+\fBParameters\fP
+.RS 4
+\fIinterval\fP Interval 
+.RE
+.PP
+\fBSee also\fP
+.RS 4
+\fBinterval()\fP 
+.RE
+.PP
+
+.SS "void QwtSamplingThread::stop ()\fC [slot]\fP"
+Terminate the collecting thread 
+.PP
+\fBSee also\fP
+.RS 4
+QThread::start(), \fBrun()\fP 
+.RE
+.PP
+
+
+.SH "Author"
+.PP 
+Generated automatically by Doxygen for Qwt User's Guide from the source code\&.