EventHandler.init no longer pre-creates Priority Queues

Removed the code to pre-prepare all of the Priority Queues and Stacks from `EventHandler`. This means that only Priority Queues and Stacks existing will be those which actually contain `Eventable` objects waiting to be processed.
Ultimately, this speeds up iteration by eliminating the empty Priority Queues/Stacks. If it is iterated, it contains an `Eventable` to process.

Author: LK-Simon

Sources/EventDrivenSwift/EventHandler/EventHandler.swift

@@ -177,10 +177,6 @@ open class EventHandler: ObservableThread, EventHandlable {
 
     override init() {
         super.init()
-        for priority in EventPriority.allCases {
-            queues[priority] = [any Eventable]()
-            stacks[priority] = [any Eventable]()
-        }
         start()
     }
 }