Replace various iterators with range-based loops (bug #63738) Replace various iterator-based loops with range-based loops where possible, for brevity. * libgui/src/documentation-bookmarks.cc: Use range-based loop * libgui/src/documentation.cc: Use range-based loop * libgui/src/files-dock-widget.cc: Use range-based loop * libgui/src/history-dock-widget.cc: Use range-based loop * libinterp/corefcn/gl-render.cc: Use range-based loop * libinterp/corefcn/gl2ps-print.cc: Use range-based loop * libinterp/corefcn/graphics.cc: Use range-based loop * libinterp/corefcn/sysdep.cc: Use range-based loop * libinterp/dldfcn/__init_fltk__.cc: Use range-based loop * libinterp/octave-value/cdef-class.cc: Use range-based loop * libinterp/octave-value/cdef-package.cc: Use range-based loop * libgui/src/find-files-model.cc: Add FIXME to note sorted insertion. * src/octave-svgconvert.cc: Use range-based loop, add FIXME to note duplicate code, eliminate loop with call to 2-argument constructor.