Add tasks for all the new languages

Task/Combinations/Sidef/combinations-2.sidef

@@ -0,0 +1,17 @@
+func combine(n, set) {
+
+    set.len || return []
+    n == 1  && return set.map{[_]}
+
+    var (head, result)
+    head   = set.shift
+    result = combine(n-1, [set...])
+
+    for subarray in result {
+        subarray.prepend(head)
+    }
+
+    result + combine(n, set)
+}
+
+combine(3, @^5).each {|c| say c }