listener_remove is not triggered when kicking users

When kicking users, listener_remove isn't triggered. This has been tested on Icecast 2.3.3.

I haven't tested if this works if you remove a mount point, but one would like the same functionality here, that listener_remove is triggered as well. I use these triggers to update a database with listeners and to make sure I have consistency, it would be nice if both triggers (listener_add and listener_remove) were triggered whatever causes a listener to be added and removed.