Event description is now correctly set and get from Outlook

Please @blaxter review as I'd like to include the unit tests you wrote for this to avoid regressions.

* Get event description from SOGo is not segfaulting
* RTF parsing is now working better for parsing control words and once we encounter NULL final char.
The original code is ignoring \0 chars and moving forward in the buffer given to be parsed (so I guess it is possible to have \0 bytes in the middle, I don't know why but the original comment suggest that).

With this change you are trying to end the parsing with the first \0 byte.