Feature request: remove old events from mpf monitor

[worldpeace-germany]

Hi,

when testing it sometimes would be helpful to start again with an empty list of events. Would be nice if the mpf monitor event list has a button "clear" which removes from that view all events posted so far. Maybe it would as well be helpful to have an additional column which shows the timestamp of the event posted. I know they are ordered as received, but seeing the time difference might be helpful to understand what action has posted such an event.

Thanks for the great tool!