Completely removed the html5lib sanitizer.
Fixed the string-handling to work in both
Ruby 1.8.x and 1.9.2. There are still,
inexplicably, two functional tests that
fail. But the rest seems to work quite well.
Apply the same methodology, as in Revision 432,
to the category chunk-handler. This completes
the replacement of all the code that looks like
if string.is_utf8?
do something
else
complain
end
with code that looks like
string.purify
do something
