The gcc version was using clang underneath also. If we wanted to use
gcc, we would need to ensure cmake picks it up properly. We do not
really need to test gcc on macOS, as long as things build correctly
there with the default compiler (clang).
- improved documentation
- changed: using static const variables instead of \c #define for fixed default values (e.g. JKQTPImageTools::LUTSIZE, JKQTPImageTools::PALETTE_ICON_WIDTH, JKQTPlotterDrawinTools::ABS_MIN_LINEWIDTH, JKQTMathText::ABS_MIN_LINEWIDTH ...)
- new: added debugging option, which surrounds different regions with visible rectangles (JKQTBasePlotter::enableDebugShowRegionBoxes() )
- fixed: colorbars at top were positioned over the plot label
- new: frames (plot viewport, key/legend ...) may be rounded off at the corners
- new: diverse new styling options (default font name/size ...)
- speed improvements to JKQTMathText::useSTIX()
