Add tasks for all the new languages

Task/Apply-a-callback-to-an-array/Swift/apply-a-callback-to-an-array.swift

@@ -0,0 +1,13 @@
+func square(n: Int) -> Int {
+    return n * n
+}
+
+let numbers = [1, 3, 5, 7]
+
+let squares1a = numbers.map(square)         // map method on array
+
+let squares1b = numbers.map {x in x*x}      // map method on array with anonymous function
+
+let squares1b = numbers.map { $0 * $0 }      // map method on array with anonymous function and unnamed parameters
+
+let isquares1 = numbers.lazy.map(square)   // lazy sequence