Know whether notification was closed by user or clearNotifications()

[hjaltisan]

It would be really nice to be able to distinguish between onRemove() that was called because a user clicked on a notification, and a onRemove() that was called from clearNotifications()

Two possible solutions would be:

1. Add a second parameter to onRemove that would tell who/what is responsible for calling the onRemove (autoDismiss, userClick, clearNotifications)
2. Add a parameter to clearNotifications(triggerOnRemove = true) so that we can choose when calling clearNotifications if we want it to invoke onRemove or not