Change the license to LGPLv2.1+

Greg gave me permission to distribute the files under public domain (see
http://www.freelists.org/post/liblouis-liblouisxml/Fwd-Re-License-of-Afrikaans-Cherokee-Hawaiian-Maori-Sotho-and-Tswana-tables).
To align the license with the rest of the tables I am changing the
license of his tables to LGPL version 2.1