Add SVG convertion option for printing to PDF and raster outputs (bug #52193) * print.m (docstring): Mark Gnuplot only devices with "*". For ps formats document the limited text support. Add "pdfcrop" device (no surrounding page) and remove "pdfwrite" from the examples of ghostscript devices. (print): in warnings, replace "print:" namespace by "octave:print:". Only change grid lines transparency for "ps2write" device. Add svgconvert_cmd field to opt structure (svgconvert): new function to build the svg convertion command * __print_parse_opts__.m: In warnings, replace "print:" namespace by "octave:print:". Add svgconvert_binary to arg_st structure. (__svgconv_binary__): New function to locate the svg conversion binary either using OCTAVE_ARCHLIBDIR environment variable or in Octave's archlibdir. * __opengl_print__.m: For other ghostscript devices than ps2write, first convert SVG to PDF and pass the PDF to ghostscript instead of an EPS. * src/octave-svgconvert.cc: New file with the command line converter code. * src/module.mk: Build converter based AMCOND_BUILD_QT_GUI condition. Setup related SOURCE, CPPFLAGS, LDADD, LDFLAGS variables with Qt headers and libraries. * m4/acinclude.m4: Add QtXml to necessary Qt modules.

--- a/m4/acinclude.m4	Wed Oct 31 23:07:19 2018 +0100
+++ b/m4/acinclude.m4	Fri Nov 17 11:03:30 2017 +0100
@@ -1975,11 +1975,11 @@
   case "$qt_version" in
     4)
       QT_OPENGL_MODULE="QtOpenGL"
-      QT_MODULES="QtCore QtGui QtNetwork QtHelp"
+      QT_MODULES="QtCore QtGui QtNetwork QtHelp QtXml"
     ;;
     5)
       QT_OPENGL_MODULE="Qt5OpenGL"
-      QT_MODULES="Qt5Core Qt5Gui Qt5Network Qt5PrintSupport Qt5Help"
+      QT_MODULES="Qt5Core Qt5Gui Qt5Network Qt5PrintSupport Qt5Help Qt5Xml"
     ;;
     *)
       AC_MSG_ERROR([Unrecognized Qt version $qt_version])