[trunk_admin] Update mn_MN, thanks to : Ulzii

git-svn-id: http://piwigo.org/svn/trunk@22540 68402e56-0260-453c-a942-63ccdbb3a9ee
admin theme links use text-decoration on hovering instead of border-bottom (css simpler, no box sizing issues on hover ...)

git-svn-id: http://piwigo.org/svn/trunk@22541 68402e56-0260-453c-a942-63ccdbb3a9ee
[trunk] - Language_-

git-svn-id: http://piwigo.org/svn/trunk@22551 68402e56-0260-453c-a942-63ccdbb3a9ee