Add tasks for all the new languages

Task/Sorting-algorithms-Quicksort/Lobster/sorting-algorithms-quicksort.lobster

@@ -0,0 +1,15 @@
+include "std.lobster"
+
+def quicksort(xs, lt):
+    if xs.length <= 1:
+        xs
+    else:
+        pivot := xs[0]
+        tail := xs.slice(1, -1)
+        f1 := filter tail:  lt(_, pivot)
+        f2 := filter tail: !lt(_, pivot)
+        append(append(quicksort(f1, lt), [ pivot ]),
+                      quicksort(f2, lt))
+
+sorted := [ 3, 9, 5, 4, 1, 3, 9, 5, 4, 1 ].quicksort(): _a < _b
+print sorted