Add tasks for all the new languages

Task/Stack/Phix/stack-2.phix

@@ -0,0 +1,26 @@
+function push(sequence stack, object what)
+    stack = append(stack,what)
+    return stack
+end function
+
+function pop(sequence stack)
+    object what = stack[$]
+    stack = stack[1..$-1]
+    return {stack,what}
+end function
+
+function empty(sequence stack)
+    return length(stack)=0
+end function
+
+sequence stack = {}
+?empty(stack)               -- 1
+stack = push(stack,5)
+?empty(stack)               -- 0
+stack = push(stack,6)
+integer top
+{stack,top} = pop(stack)
+?top                        -- 6
+{stack,top} = pop(stack)
+?top                        -- 5
+?empty(stack)               -- 1