Grbl mega 5x compatibility

[Shkolik]

Hello! Thank you for you work - using ioSender on my 3 axis cnc running teensy just fine. But now I playing with 5 axis foam cutter running latest GRBL Mega 5X and having issue right from connect. Looks like ioSender parse OPT incorrectly (also reproducible on my old 3 axis cnc running grbl 1.1h). Controller sends OPT with value "VNMGL,35,255,64" and code try to parse 64 as NumAxes that obviously incorrect.

according to https://github.com/fra589/grbl-Mega-5X/wiki/grbl-Mega-5X-v1.2-interface

• [OPT:] line follows immediately after and contains character codes for compile-time options that were either enabled or disabled. - The codes are defined below and a CSV file is also provided for quick parsing. This is generally only used for diagnosing firmware bugs or compatibility issues. - The value after the first comma contains the blockBufferSize, as int. - The value after the second comma contains the rxBufferSize, as int. - The value after the third comma contain the settings.flags, as int.

so there we should parse flags, not number of axis but flags. Not sure what to do next - have no exp with grbl protocol. For now I just replaced

if (s.Length > 3 && NumAxes != int.Parse(s[3], CultureInfo.InvariantCulture))

with

if (s.Length > 3 && int.TryParse(s[3], out int flags) && NumAxes != flags && flags < 10 && flags > 0)

to make it run, but I'm sure you know more elegant solution to this problem.

PS: Want to adapt ioSender as much as possible to FoamCutter mode, if you don't mind - digging trough code. If you interested in additional mode - let me know and I'll contribute as much as I can.