Add tasks for all the new languages

Task/Sorting-algorithms-Selection-sort/Sidef/sorting-algorithms-selection-sort.sidef

@@ -0,0 +1,20 @@
+class Array {
+    method selectionsort {
+        for i in ^(self.end) {
+            var min_idx = i
+            for j in (i+1 .. self.end) {
+                if (self[j] < self[min_idx]) {
+                    min_idx = j
+                }
+            }
+            self.swap(i, min_idx)
+        }
+        return self
+    }
+}
+
+var nums = [7,6,5,9,8,4,3,1,2,0];
+say nums.selectionsort;
+
+var strs = ["John", "Kate", "Zerg", "Alice", "Joe", "Jane"];
+say strs.selectionsort;