[Grbl_Esp32 Issue#101] Include $N functions

I’m interested on using the $N Startup function from GRBL using your board and your code (must say it works wonderful to be honest!!)

I’ve seen that the “original” GRBL, can use the $N Functions to assign a “startup” functions such as Homing, or Assign mm/inch etc…

I think it would be useful to use that function to send some code in terms of “self-working” machines, that run over and over the same code.

(I plan to use it personally to send the “$FM, $F, and $F/heremygcode.gcode” codes needed to start a gcode stored in the microSD)

Thanks!