Smoothieware does not support GRBL config commands about octoprint-bettergrblsupport

[hgroover]

I cloned develop and changed a few lines to support Smoothie and it all seems to work locally (except the config parsing, I didn't expect that to work but it doesn't raise an error). The documentation from the Smoothie project was incorrect, cat /sd/config.txt is the correct substitute for $$.

Working on adding the checkbox(es) to enable this behavior into the configuration UI and running more tests, and I can do a PR when I'm done if you're interested. This is a really great plugin and very useful! Currently I've been suffering through the Smoothie native web interface which is not always responsive and doesn't handle large file uploads.

[synman]

if you share your code, either here, or via pull request I'm more than happy to add this to the master branch