#175 Add command line parameter for choose config directory

[Alexey Diyachenko]

I have 3018 mini-cnc and sculpfun laser.
For both devices i need different configurations with tools setup and post processors.

I created one command line parameter to add suffix line to config directory name.
Now i can use ".config/dxf2gcode" and ".config/dxf2gcode.laser" configurations.

Merge request sendet to https://github.com/ltspicer/dxf2gcode