Bulgarian language update

inc/lang/bg/register.txt

inc/lang/bg/resendpwd.txt

inc/lang/bg/revisions.txt

inc/lang/bg/searchpage.txt

inc/lang/bg/showrev.txt

inc/lang/bg/stopwords.txt

inc/lang/bg/updateprofile.txt

inc/lang/bg/uploadmail.txt

lib/plugins/acl/lang/bg/lang.php

lib/plugins/config/lang/bg/intro.txt

lib/plugins/config/lang/bg/lang.php

lib/plugins/plugin/lang/bg/lang.php

lib/plugins/popularity/lang/bg/intro.txt

lib/plugins/popularity/lang/bg/lang.php

lib/plugins/popularity/lang/bg/submitted.txt

lib/plugins/revert/lang/bg/lang.php

lib/plugins/usermanager/lang/bg/lang.php