[#4983] Feature: Add a hook point that would allow a HTML subpart to the notification e-mail

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/seminars/trunk@83828 735d13b6-9817-0410-8766-e36946ffe9aa
Bump the version number to 0.9.89.

git-svn-id: https://svn.typo3.org/TYPO3v4/Extensions/seminars/trunk@83829 735d13b6-9817-0410-8766-e36946ffe9aa