Needs two tides to strikeout.
Much of the code was changed (somewhat crudely) to better match the way the real smushit, but at least it now works as expected.
I wrote some rather crude test files just so I could get a sense of the way it was expected to work. Hopefully I'll switch to proper PHP Unit tests one day.
Yahoo claims the Smush.it trademark, so we'll simply call this "Smush" to avoid confusion.