Add .gcode to file format list

[themachinist]

@gesslertell:

@the_machinist_ Hey I love to use your Sublime-Text GCode Syntax highlighter.. But I seem to be unable to add a ".gcode" to the auto select

[ElectricRCAircraftGuy]

I see gcode in the extension list, here: https://github.com/themachinist/gcode-syntax-highlighting/blob/master/GcodeSyntaxHighlightingDef.tmLanguage#L11

Can this issue be closed?