Fix #19: Issue 19 copy less in site gen

The extra random stuff copied over when generating the site has been fixed. Basically caused by the cache of the gen directory preserving old attempts. We've removed the old stuff from the cache and now the public directory has just the right stuff.

However, in cleaning it up, we found out that we weren't copying enough stuff from cmucl-www/www to the gen directory (and therefore to the public directory). Now copy everything over from cmucl-www/www to gen.

So leave the branch around so we have a record of how the gen directory was cleaned out, and also fix the issue of missing files (like cmucl.css, the images, etc.).