Perform Unicode normalization

[mrumpf]

Perform Unicode normalization: http://ahinea.com/en/tech/accented-translate.html
This should be done before adding files to the Lucene index as otherwise searching will be hard for languages with diacritic characters.

But also filenames in the file-system might be written without any diacritic characters to allow easy file searches.

This can be implemented by using the Java5/ICU4J Library class Normalizer:

• http://icu-project.org/apiref/icu4j/com/ibm/icu/text/Normalizer.html
• http://www.rgagnon.com/javadetails/java-0456.html (http://download.oracle.com/javase/1.5.0/docs/api/java/text/Collator.html)