Fix word boundaries.

This fixes word boundaries by replacing the RegEx `\b` with a unicode compatible RegEx. This RegEx is derived from the special characters string in the old pattern files. It is also checked against the [unicode word breaking data file](http://www.unicode.org/Public/6.2.0/ucd/auxiliary/WordBreakProperty.txt). All characters are in the unicode word breaking data file, but not all characters from the data file are in the RegEx (thus it performs as well as before, but not better --- there is a size increase of 1-2 Kb for accurate word breaking based on the official data).