Grave accent on single/last words should be normalized to acute

[ryanfb]

We have a lot of duplicated "unique" headwords where we have an acute-accented version of a word as well as a grave-accented version. For single/last words in a headword, the grave should be normalized to acute to remove these duplicates - the grave is because the headword is run together with the entry (or accented as though it is).