Ignore accents for address book search

[VolkerGoetz]

During search in the address book, accents and umlauts, etc. must be entered correctly to find a person. It would be much more convenient if the matching algorithm was more relaxed so that typing a base character would match all accented characters (like it is in the address book itself).

example Typing "a" would match "a", "á", "à", "å" and so on "Andre" would match "André" as well as "Andreas" (at the moment it matches only the latter)