Implement schedule main thread task with return value (#1579)

* Implement schedule main thread task with return value

* Revert change of TestBot.cs

MinecraftClient/TaskWithResult.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading;
+
+namespace MinecraftClient
+{
+    public class TaskWithResult
+    {
+        private Delegate Task;
+        private AutoResetEvent ResultEvent = new AutoResetEvent(false);
+
+        public object Result;
+
+        public TaskWithResult(Delegate task)
+        {
+            Task = task;
+        }
+
+        /// <summary>
+        /// Execute the delegate and set the <see cref="Result"/> property to the returned value
+        /// </summary>
+        /// <returns>Value returned from delegate</returns>
+        public object Execute()
+        {
+            Result = Task.DynamicInvoke();
+            return Result;
+        }
+
+        /// <summary>
+        /// Block the program execution
+        /// </summary>
+        public void Block()
+        {
+            ResultEvent.WaitOne();
+        }
+
+        /// <summary>
+        /// Resume the program execution
+        /// </summary>
+        public void Release()
+        {
+            ResultEvent.Set();
+        }
+    }
+}