Coroutines now wait for their children

JobSuport.attachChild is introduced;
Job "Completing" state is introduced;
withTimeout is a proper coroutine;
Better diagnostics in cancellation and unexpected exception messages;
Fixed cancellable suspending function to throw CancellationException;
Job.getCompletionException renamed to Job.getCancellationException;
Introduced Deferred.getCompletionExceptionOrNull
Updated docs for Job & Deferred to explain parent/child;
Deprecate and hide legacy Job.invokeOnCompletion signatures;
Updated guide for parent-child relations and related stuff
diff --git a/core/kotlinx-coroutines-core/src/test/kotlin/guide/example-cancel-07.kt b/core/kotlinx-coroutines-core/src/test/kotlin/guide/example-cancel-07.kt
new file mode 100644
index 0000000..1a197a4
--- /dev/null
+++ b/core/kotlinx-coroutines-core/src/test/kotlin/guide/example-cancel-07.kt
@@ -0,0 +1,31 @@
+/*
+ * Copyright 2016-2017 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// This file was automatically generated from coroutines-guide.md by Knit tool. Do not edit.
+package guide.cancel.example07
+
+import kotlinx.coroutines.experimental.*
+
+fun main(args: Array<String>) = runBlocking<Unit> {
+    val result = withTimeoutOrNull(1300L) {
+        repeat(1000) { i ->
+            println("I'm sleeping $i ...")
+            delay(500L)
+        }
+        "Done" // will get cancelled before it produces this result
+    }
+    println("Result is $result")
+}