Since the pause status is more intuitive for the end-user than the
running state (which is used internally) the interface of the dunstctl
is renamed to set-paused and is-paused (previously set-running and
running).
This requires inversion of the boolean variables to be consistent with
the inverted naming.
Fixes#710
Currently triggers only the latest notification. TODO: implement it
either with ActionsAll or more favorable: with an optional paramter,
which should trigger only the action of a single notification.
The problem currently: I have got no ability to check the DBus docs, as
I'm on a bad internet connection.
