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/QwtIntervalSample.3

@@ -0,0 +1,57 @@
+.TH "QwtIntervalSample" 3 "Mon Jun 1 2020" "Version 6.1.5" "Qwt User's Guide" \" -*- nroff -*-
+.ad l
+.nh
+.SH NAME
+QwtIntervalSample \- A sample of the types (x1-x2, y) or (x, y1-y2)  
+
+.SH SYNOPSIS
+.br
+.PP
+.PP
+\fC#include <qwt_samples\&.h>\fP
+.SS "Public Member Functions"
+
+.in +1c
+.ti -1c
+.RI "\fBQwtIntervalSample\fP ()"
+.br
+.ti -1c
+.RI "\fBQwtIntervalSample\fP (double, const \fBQwtInterval\fP &)"
+.br
+.RI "Constructor\&. "
+.ti -1c
+.RI "\fBQwtIntervalSample\fP (double \fBvalue\fP, double min, double max)"
+.br
+.RI "Constructor\&. "
+.ti -1c
+.RI "bool \fBoperator==\fP (const \fBQwtIntervalSample\fP &) const"
+.br
+.RI "Compare operator\&. "
+.ti -1c
+.RI "bool \fBoperator!=\fP (const \fBQwtIntervalSample\fP &) const"
+.br
+.RI "Compare operator\&. "
+.in -1c
+.SS "Public Attributes"
+
+.in +1c
+.ti -1c
+.RI "double \fBvalue\fP"
+.br
+.RI "Value\&. "
+.ti -1c
+.RI "\fBQwtInterval\fP \fBinterval\fP"
+.br
+.RI "Interval\&. "
+.in -1c
+.SH "Detailed Description"
+.PP 
+A sample of the types (x1-x2, y) or (x, y1-y2) 
+.SH "Constructor & Destructor Documentation"
+.PP 
+.SS "QwtIntervalSample::QwtIntervalSample ()\fC [inline]\fP"
+Constructor The value is set to 0\&.0, the interval is invalid 
+
+.SH "Author"
+.PP 
+Generated automatically by Doxygen for Qwt User's Guide from the source code\&.