Eliminate unintentional entity tick time increase

src/main/kotlin/ru/dbotthepony/kstarbound/world/entities/AbstractEntity.kt

@@ -254,17 +254,30 @@ abstract class AbstractEntity : Comparable<AbstractEntity> {
 		}
 	}
 
-	// for fast check on completed tasks
 	// This is necessary to cancel tasks when we are removed, so we don't reference ourselves
 	// in event loop after we have been removed
-	private val scheduledTasks = PriorityQueue<ScheduledFuture<*>>()
+	private val scheduledTasks = ObjectArrayList<ScheduledFuture<*>>()
 
 	protected fun scheduleInTicks(ticks: Int, action: Runnable) {
-		scheduledTasks.add(world.eventLoop.schedule(action, ticks * Starbound.TIMESTEP_NANOS, TimeUnit.NANOSECONDS))
+		var task: ScheduledFuture<*>? = null
+
+		task = world.eventLoop.schedule(Runnable {
+			scheduledTasks.remove(task!!)
+			action.run()
+		}, ticks * Starbound.TIMESTEP_NANOS, TimeUnit.NANOSECONDS)
+
+		scheduledTasks.add(task)
 	}
 
 	protected fun schedule(time: Long, unit: TimeUnit, action: Runnable) {
-		scheduledTasks.add(world.eventLoop.schedule(action, time, unit))
+		var task: ScheduledFuture<*>? = null
+
+		task = world.eventLoop.schedule(Runnable {
+			scheduledTasks.remove(task!!)
+			action.run()
+		}, time, unit)
+
+		scheduledTasks.add(task)
 	}
 
 	var isRemote: Boolean = false
@@ -382,10 +395,6 @@ abstract class AbstractEntity : Comparable<AbstractEntity> {
 	open fun damagedOther(notification: DamageNotificationPacket) {}
 
 	open fun tick(delta: Double) {
-		while (scheduledTasks.isNotEmpty() && scheduledTasks.peek().isDone) {
-			scheduledTasks.poll()
-		}
-
 		if (networkGroup.upstream.isInterpolating) {
 			networkGroup.upstream.tickInterpolation(delta)
 		}