Add tasks for all the new languages

Task/Accumulator-factory/Nim/accumulator-factory.nim

@@ -0,0 +1,19 @@
+proc accumulator(sum: float): auto =
+  var sum = sum
+  return proc (n: float): float =
+    sum += n
+    return sum
+
+var x = accumulator(1)
+echo x(5) # 6
+echo x(2.3) # 8.3
+
+var y = accumulator(1)
+echo y(5) # 6
+echo y(2.3) # 8.3
+
+var z = accumulator(3)
+echo z(5) # 8
+echo z(2.3) # 10.3
+echo x(0) # 8.3
+echo z(0) # 10.3