This class would use the location information provided by
regex(3) as range for for a substring. However, the information
regex(3) returns is a byte-based, while NSString works on characters.
This can cause a problem when there are UTF-8 characters in the string,
as the wrong subsstring will be returned.
This is fixed by taking the UTF bytesequence, and extracting a substring
from that, rather than using NSString's own substring method
Pieter de Bie