Added Time.delay as a convenience feature for cross-platform delayed …

…Future

core/js/src/main/scala/io/youi/YouIPlatform.scala

@@ -0,0 +1,14 @@
+package io.youi
+
+import scala.concurrent.{Future, Promise}
+import org.scalajs.dom._
+
+object YouIPlatform {
+  def delay(millis: Long): Future[Unit] = {
+    val promise = Promise[Unit]
+    window.setTimeout(() => {
+      promise.success(())
+    }, millis)
+    promise.future
+  }
+}

core/jvm/src/main/scala/io/youi/YouIPlatform.scala

@@ -0,0 +1,17 @@
+package io.youi
+
+import java.util.{Timer, TimerTask}
+
+import scala.concurrent.{Future, Promise}
+
+object YouIPlatform {
+  private lazy val timer = new Timer("io.youi.Time", true)
+
+  def delay(millis: Long): Future[Unit] = {
+    val promise = Promise[Unit]
+    timer.schedule(new TimerTask {
+      override def run(): Unit = promise.success(())
+    }, millis)
+    promise.future
+  }
+}

core/shared/src/main/scala/io/youi/util/Time.scala

@@ -0,0 +1,17 @@
+package io.youi.util
+
+import scala.concurrent.Future
+import scala.concurrent.duration.FiniteDuration
+
+/**
+  * Cross-platform functionality for dealing with time
+  */
+object Time {
+  /**
+    * Creates a non-blocking Future that is completed after `duration` is elapsed
+    *
+    * @param duration an amount of time that must elapse before the future is complete
+    * @return Future[Unit] that will be complete after `duration`
+    */
+  def delay(duration: FiniteDuration): Future[Unit] = io.youi.YouIPlatform.delay(duration.toMillis)
+}