[br] improved disambiguation of word "a" to find error in:
     *Un den hag a plij dezhañ...* -> Un den hag a blij dezhañ..."


git-svn-id: https://languagetool.svn.sourceforge.net/svnroot/languagetool/trunk/languagetool@9699 2fe6a88b-1217-0410-b804-ba6ed01314b8