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/build.gradle b/build.gradle
index 187ce66..3911a66 100644
--- a/build.gradle
+++ b/build.gradle
@@ -14,6 +14,7 @@
         jcenter()
         maven { url "https://kotlin.bintray.com/kotlinx" }
         maven { url "https://kotlin.bintray.com/kotlin-dev" }
+        maven { url "https://kotlin.bintray.com/kotlin-eap" }
         maven { url "https://jetbrains.bintray.com/kotlin-native-dependencies" }
         maven { url "https://plugins.gradle.org/m2/" }
     }
@@ -53,7 +54,7 @@
 
     repositories {
         jcenter()
-        maven { url "https://kotlin.bintray.com/kotlin-dev" }
+        maven { url "https://kotlin.bintray.com/kotlin-eap" }
         maven { url "https://kotlin.bintray.com/kotlinx" }
     }
 }