Doormat is a guest-counter for any website. Just call the `dm.lisp`
file with a URL as it's sole argument, and it'll both add another visitor
to the count & serve you the current guest-count.
If you add the "?img" argument before the URL, then it'll fetch a PNG
image of the guest-count: so you can put an <img> tag in your webpage
with the URL to a Doormat instance, and let it handle guest-counts,
even with static HTML pages!
Set up a MySQL database called `doormat`, and create this table:
`create table entries (url text, visitors int unsigned);`
Check the `web/` directory for more instruction.