RFC: strips html tags from systray tooltip if not supported

[Carlo]

Hi,
some kde apps use rich text tooltips, windows doesn't supports
this(maybe osx too?) so the user will see the text with all the html
tags
so I was thinking if we should strip these tags on platforms that
don't support it, but I don't know where would be the right place to
do it, it can either be done by adding a setToolTip method in
KSystemTrayIcon or directly in QSystemTrayIcon, but I'm not sure if
it's something that would be accepted for Qt