Add Dockerfile

[Arian-D]

Hey, the current image on dockerhub that is mentioned in the README is 4 years old. I made this little Dockerfile to avoid the hassle of setting up quicklisp, roswell, qlot, ncurses, etc. You can run the following to build and run it.

docker build -t lem .
docker run --rm -it -v .:/shared lem

[cxxxr]

Thank you!