Allow gcode comments in (parenthesis) since some controllers error on semicolon comments

Following a thread on Makerforums, this looks like an feature request we should, at least, capture.
https://forum.makerforums.info/t/changeable-standard-sign-for-comments-in-gcode/86432/

I'm thinking about a comments replacement string setting, something like `; $comment` which can be changed to `( $comment ) etc at will.