Please add a valid unpreprocessed gcode file for testing

[mrvn]

I'm having a hard time generating a gcode file that doesn't look up the printer and has the right extrusion (or any at all) speed. Please add a simple sample stl file and unpreprocessed gcode file so one has a known to be working input file (excluding the slicer as a problem source).

It probably makes sense then to also include the processed file and add a testsuite that checks m3d-linux works and have github run the testsuit automatically for every commit. This is a great way to ensure no regressions occur.