Just a note to say how useful this plugin has turned out to be. I thought I had a clean library. It was clean to 99%, but not totally. The changes to force to ASCII helped me find several cases where an author appeared with and without accented characters. The soundex matches helped find cases of slight author and title misspellings. Having author-only and title-only helped with finding problems with books in both French and English. Working with other combinations found a few other problems. And on top of all that, it is very fast.
Very fine work!