EventPlot: Add ability to plot simultaneous events

Created by: sinkap

The timeline plot was designed to have one "key" running in one "lane". Here you have the "queueing" key running in multiple lanes and this confuses the filtering logic. I imagined the each event to be only present in one lane at a time, much like a single PID can be only on a single CPU.

This fix allows the EventPlot to plot concurrent events. Events which occur simultaneously in multiple lanes