Dockerfile and a script for running the script inside a Docker container

[kaplas]

Hi! First of all thank you for your work on this script, it has helped me a lot!

I wanted to run this script inside a Docker container, because I don't want to install a million different development environments on my host machine. I figured out this could be of some use to others stumbling upon your repository as well.

If you may, this PR will do the following things:

• Add a Dockerfile for installing all the required dependencies in a Docker container
• Add a run-in-docker.sh script for running the whole thing easily. The script may look a bit complex, because one needs to get the input file inside of the container before it's run.
• Add a paragraph of related documentation to README.md
• Clarifies README.md a bit by adding subheaders and some formatting

Hope you like this! If there's anything that needs to changed for this to be merged, please just let me know.

Have a nice summer, and once again, thank you for you work :)

[lar3ry]

Thanks for this. I am a novice on github (as well as python). I added another Python file, stlplace.py, and was about to delete stldim.py when I notice your pull request. Looks good. Now I am not sure how to proceed.

[lar3ry]

Darn. I expected my repository to be changed when I clicked on Commit.

[lar3ry]

Darn. I expected my repository to be changed when I clicked on Merge pull request.