* add Wcscoll() and Wcsxfrm() ICU locale backend
* provide implementations of wcscoll() and wcsxfrm() that are using
the respective methods of the locale backend
* update copyrights of locale backend files
Multibyte-support has been rewritten to use ICU as backend.
While this does not necessarily work properly in every aspect
(e.g. the shell still has [different] problems with multibyte-
characters now), it does fix#6263 and #7700.
