set version number to 1.6

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/ke_search/trunk@81920 735d13b6-9817-0410-8766-e36946ffe9aa
upgrade verson number to 1.6.1dev

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/ke_search/trunk@81921 735d13b6-9817-0410-8766-e36946ffe9aa