[ticket/11201] Revert WLM removal. It is still in use in china.

Windows Live Messenger is still in use in china which accounts for ~20% of world
population. Revert WLM dropping which has been merged under the assumption that
WLM data and features are completely useless (see #1185).

This commit reverts commits
 - 460470229d972b93ef5a98b0d1d97a2a970d684f
 - 9affd6f7e7b95442f1ef14894858d8213f3fbd2a

which have been merged by d59431691c27c73fba8ae9934b84b34a13280dd2.

PHPBB3-11201

http://tracker.phpbb.com/browse/PHPBB3-11201