Update of LTLI

I did my action item to add "or its successor" in appropriate places.
Please have a look at http://www.w3.org/International/core/langtags/ . I
also made some change suggested by Richard at
"http://www.w3.org/2006/12/12-i18ncore-minutes#item06":
- richard: BP statements should be first, explanations later


Felix