Migration to new multiplatorm plugin (#947)

Migration to a new multiplatform plugin
  
  * kotlinx-coroutines-core-[common|js|native] are merged into one core module with multiple source sets
  * Folder structure and readme are restructured
  * Publication process is patched to preserve backward compatibility with artifact names
diff --git a/gradle/compile-js.gradle b/gradle/compile-js.gradle
index 936370d..4b1e3bd 100644
--- a/gradle/compile-js.gradle
+++ b/gradle/compile-js.gradle
@@ -1,10 +1,10 @@
 /*
- * Copyright 2016-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ * Copyright 2016-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
  */
 
 // Platform-specific configuration to compile JS modules
 
-apply plugin: 'kotlin-platform-js'
+apply plugin: 'kotlin2js'
 
 dependencies {
     compile "org.jetbrains.kotlin:kotlin-stdlib-js:$kotlin_version"
@@ -26,4 +26,3 @@
         outputFile = new File(outputFile.parent, baseName + ".js")
     }
 }
-