Added documentation to stepper.h

Almost done with the documentation. I am just going to paste all
of this in my notebook in a futile attempt to document this project.
I might write some documentation on the java side as well/
Added interrupt logic to move

Make sure that we are able to interrupt the
bartender_move_to_location() function by setting the bartender status
flag. Might rewrite this in the future to support multiple interrupts.
Added more comments to explain the code

Usally a good thing. Maybe not.