Mark individual topics as read without opening them

When going through lists of topics, either in the search results from "Posts since last visit' or directly in the forums, it would be useful to be able to mark topics read without actually opening them. The idea is that if you're not interested in a topic, you on the one hand don't want them cluttering your view of what topics there are, but on the other hand don't want to open them, and then refresh the view or search (and perhaps navigate back to the right page of the search results after that).

It would be nice if it were possible to directly mark topics are read, and have them immediately update their status in the current view: completely removed in case of search results like "posts since last visit", or greyed out in other views.

See also topic https://bugreports.qt-project.org/browse/QTWEBSITE-126