IcyDwarfPlot v14.3.1

The plotting functions of IcyDwarf are now removed from the main
program, IcyDwarf, and implemented in this program, IcyDwarfPlot.
This allows IcyDwarf to be run without needing Simple DirectMedia Layer
2 (SDL2), needed by the plotting functions. It also allows IcyDwarfPlot
to be run on any IcyDwarf output files without having to re-run IcyDwarf
each time.
Merge remote-tracking branch 'choose_remote_name/master'