Add script to generate html and pdf files from markdown.

[studersi]

This is to address issue #6.

The script generates html files from the markdown source and pdf files from html source.

Note that there are still some issues with this script:

• [ ] HTML files are not styled at all
• [ ] HTML files contain the filename
• [ ] HTML files are missing some images
• [ ] HTML files do not have an index page
• [ ] HTML output directory folder structure does not necessarily correspond to folder structure on website
• [ ] PDF files contain header and footer with metadata from printing
• [ ] PDF files only contain single tutorials, they are not joined into a single file

Some of these problems are fairly easy to address but require decisions to be made first (e.g. how to structure the output directories).