Migrate to Kotlin 1.3 coroutines, drop experimental from package

* Features based on version 0.30.0
* Uses Kotlin version 1.3.0-rc-57
* Uses Kotlin/Native version 0.9.2
* Uses AtomicFu 0.11.9-eap13
* Replace SuccessOrFailure with Result
* Replace buildSequence and buildIterator with sequence and iterator
* Apply @BuilderInference on all builders (including extension methods to workaround inference bug)
diff --git a/common/kotlinx-coroutines-core-common/test/CoroutineScopeTest.kt b/common/kotlinx-coroutines-core-common/test/CoroutineScopeTest.kt
index b3d9125..b0e4ba2 100644
--- a/common/kotlinx-coroutines-core-common/test/CoroutineScopeTest.kt
+++ b/common/kotlinx-coroutines-core-common/test/CoroutineScopeTest.kt
@@ -2,10 +2,10 @@
  * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
-package kotlinx.coroutines.experimental
+package kotlinx.coroutines
 
-import kotlinx.coroutines.experimental.internal.*
-import kotlin.coroutines.experimental.*
+import kotlinx.coroutines.internal.*
+import kotlin.coroutines.*
 import kotlin.test.*
 
 class CoroutineScopeTest : TestBase() {