Allow canceling out all other notifications

[pyro-code01]

Hello,

i think its a good idea to add method to cancel all other notifications, seems useful with fast uis where users click a lot and they get spammed, i know i can handle it manually, but it would be nice to have native method.

[brgrz]

Agree, for instance allow three (configurable number) notifications to be pushed and after that 1) silently cancel others incoming and/or 2) if there are more incoming just show one another notyf saving "There are more notifications available.." (we actually have a notifications drawer in place for such cases)