[TYPO3-calendar] cal ERROR due to missing CORE library

[tobilot]

Hi,
using cal 1.4.3, after Upgrade to Typo3 4.7.4 I cannot save events anymore in the BE.
I get an CORE Error handler (BE) which says (shortened): No such file or directory, caused by the class.tx_cal_notification_view.php line 465
This line refers to the class.t3lib_htmlmail.php in the Typo3 Core which is obviously not found.
A short investigation reveals, that this class is no longer present in Typo3 4.7.4
I also read that this class has been removed since Typo3 4.7, I didn't checked the source though, I checked only 4.7.4

Now, cal should urgently be updated to use the new Swift Mail library in order to ba able to use cal again in newer Typo3 versions.

Please check also this blog:
http://buzz.typo3.org/teams/core/article/your-first-blog/

I scanned through the issues on http://forge.typo3.org/projects/show/extension-cal, but I didn't see any entry about this which left me wondering why 
this issue wasnt recovered earlier (Typo3 4.7. has been published in April this year.

Or am I totally wrong and my error is caused by something else?

rgds
Tobias