Splitting the file into a main/test would have been a bad idea due to the smart
inlining with the standard's text.

The previous solution to always load the file is also bad for performance.

The hopefully final solution is to create an rfc2109.test system and before loading
rfc2109.lisp in it rebind *features* and push a symbol (:test) into it. The main
lisp file #+test for this symbol and defines the tests when it's loaded through
rfc2109.test.

darcs-hash:b912ce8b527d112d4aa0f74770b5eec3d8067a78

Decided to add a basic testing framework - mostly because I'm mucking about
with parsing and another library, want something to let me know when I've
REALLY screwed up.

Please note that the current stable version of FiveAM will not run these tests,
as it doesn't have the *features* that are needed to define them. I've submitted
a patch to Marco, we'll see if he adds it.

darcs-hash:d664c932b6a9c885e22a9ebc22f079096f96cdb6