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/QwtCurveFitter.3

@@ -0,0 +1,57 @@
+.TH "QwtCurveFitter" 3 "Mon Jun 1 2020" "Version 6.1.5" "Qwt User's Guide" \" -*- nroff -*-
+.ad l
+.nh
+.SH NAME
+QwtCurveFitter \- Abstract base class for a curve fitter\&.  
+
+.SH SYNOPSIS
+.br
+.PP
+.PP
+\fC#include <qwt_curve_fitter\&.h>\fP
+.PP
+Inherited by \fBQwtSplineCurveFitter\fP, and \fBQwtWeedingCurveFitter\fP\&.
+.SS "Public Member Functions"
+
+.in +1c
+.ti -1c
+.RI "virtual \fB~QwtCurveFitter\fP ()"
+.br
+.RI "Destructor\&. "
+.ti -1c
+.RI "virtual QPolygonF \fBfitCurve\fP (const QPolygonF &polygon) const =0"
+.br
+.in -1c
+.SS "Protected Member Functions"
+
+.in +1c
+.ti -1c
+.RI "\fBQwtCurveFitter\fP ()"
+.br
+.RI "Constructor\&. "
+.in -1c
+.SH "Detailed Description"
+.PP 
+Abstract base class for a curve fitter\&. 
+.SH "Member Function Documentation"
+.PP 
+.SS "virtual QPolygonF QwtCurveFitter::fitCurve (const QPolygonF & polygon) const\fC [pure virtual]\fP"
+Find a curve which has the best fit to a series of data points
+.PP
+\fBParameters\fP
+.RS 4
+\fIpolygon\fP Series of data points 
+.RE
+.PP
+\fBReturns\fP
+.RS 4
+Curve points 
+.RE
+.PP
+
+.PP
+Implemented in \fBQwtWeedingCurveFitter\fP, and \fBQwtSplineCurveFitter\fP\&.
+
+.SH "Author"
+.PP 
+Generated automatically by Doxygen for Qwt User's Guide from the source code\&.