implemented error handling when ratingobject or ratetable/ratefield are not set correcly

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/th_rating/trunk@85224 735d13b6-9817-0410-8766-e36946ffe9aa
raised z-index of tooltips

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/th_rating/trunk@85225 735d13b6-9817-0410-8766-e36946ffe9aa