Improved the Scheduler.

Adds nag message when async tasks are not properly shut down and adds a limiter for sync tasks. Once they use 35ms in a single tick, any remaining tasks are not executed until later ticks. Adds a method to report the pending tasks and one to report active worker threads

By: Raphfrk <raphfrk@gmail.com>

paper-api/src/main/java/org/bukkit/scheduler/BukkitTask.java

@@ -0,0 +1,31 @@
+package org.bukkit.scheduler;
+
+import org.bukkit.plugin.Plugin;
+
+/**
+ * Represents a task being executed by the scheduler
+ */
+
+public interface BukkitTask {
+
+    /**
+     * Returns the taskId for the task
+     *
+     * @return Task id number
+     */
+    public int getTaskId();
+
+    /**
+     * Returns the Plugin that owns this task
+     *
+     * @return The Plugin that owns the task
+     */
+    public Plugin getOwner();
+
+    /**
+     * Returns true if the Task is a sync task
+     *
+     * @return true if the task is run by main thread
+     */
+    public boolean isSync();
+}