cleaning some stuff and leftovers

Yey for one less setting? :P After @Dragooon 's changes on notification setting(s) on Board/Topic level this alone setting is just not needed...

:feet: @GitHub not cool to change :paw_prints to feet...

Signed-off-by: Antes <antes@simplemachines.org>
This line and the one below it can be removed now since we always have "unwatched" topics now.