Of course, it's impossible to leave a challenge I got so close to completing, and so I dust off the Lisp software renderer and return to the fray. I've had to grapple a bit with ASDF and learnt the hard way why upper case file names and lower case package names don't mix. Also, trying to write a tail-recursive Bressenham was interesting..only a few more bugs to wrinkle out and it can hit common-lisp.net.
Then I can go onto the freenode #lisp channel and get a critique, I hope. 123 notes at an (optimize (speed 3)) sounds like there's still a lot of work ahead..