Another productive lunch hour on #AuthorIntrusion while working on echo word detection.

I got it to correctly detect the same word used within a given range. With these plugin settings:

- scope: content
select: //token[@l>3]
within: 3
warning: 1
error: 2

And the file:

one two one three four one

It produces a warning on the first and third "one", an error on the second "one".

For xpath, I'll probably change it to `//token[length()>3]` because it's prettier.

Using C#'s XSLT function overrides and XElement has really simplified the code. I'm also happy that I've gotten rid of a big "reimplemented wheel" that the last iteration had (implementing CSS generically) since I get lost in the stupid details of getting those "right".

And since you can pull in XSLT functions through packages, that means I can easily write a package that provides "soundex()" or "stem()" or "part-of-speech()" to look for more complex items.