Add a sleep binary

dart/bin/sleep.dart

@@ -0,0 +1,15 @@
+import 'package:libac_dart/utils/IOTools.dart';
+
+Future<void> main(List<String> args) async {
+  int seconds = int.parse(args[0]);
+  prnt("\rPlease Wait $seconds second(s)...");
+
+  while(seconds>=0) {
+
+    await Future.delayed(Duration(seconds: 1));
+
+    seconds--;
+  }
+
+  prnt("\r\n");
+}