Add filtering by topics a user created or participated in

It could even be done in the user profile and as a sorting method there as well, e.g. https://tildes.net/user/cfabbro?type=participated and https://tildes.net/user/cfabbro?type=topic?sort=activity

As suggested here: https://tildes.net/~tildes/4z3/suggestion_filter_topics_by_ones_ive_participated_in