Add a --debug argument to start GUI in standard firefox tab, and not in
firefox app.
Small modifications in the interface, console messages are printed
preformted (like in a <pre/> tag).
Remove help default command from the shell, the macro command will be
used in replacement.
Remove the 'e' test command, correct the sent of grbl commands whith
arguments.
Review Runtime Status commands management, no carriage return needed.