changed searching of local db to ignore (some) special characters

This was especially a problem for german umlauts, when the database contained names with umlauts (like "Wickie und die starken Männer", while the release replaced the umlaut with two characters ("Wickie und die starken Maenner"). SQLite "LIKE" comparison does not treat that as alike (and it also fails to treat different case on other special characters correctly).

I'm not sure this is the best way to handle the problem, and I only added some special characters so far (while others may be advisable, too), but it works.