Add tasks for all the new languages

Task/Flatten-a-list/Ceylon/flatten-a-list.ceylon

@@ -0,0 +1,13 @@
+shared void run() {
+    "Lazily flatten nested streams"
+    {Anything*} flatten({Anything*} stream)
+        =>  stream.flatMap((element)
+            =>  switch (element)
+                case (is {Anything*}) flatten(element)
+                else [element]);
+
+    value list = [[1], 2, [[3,4], 5], [[[]]], [[[6]]], 7, 8, []];
+
+    print(list);
+    print(flatten(list).sequence());
+}