Add #sort to List

[moba1]

Abstract

add #sort to List.
This method returns sorted new List.

Example

List[].sort == List[]
List[1,4,2,3].sort == List[1,2,3,4]
# able to pass block
(List[1,3,2].sort { |x, y| x <=> y }) == List[1,2,3]
# sort by descending order
(List[1,3,2].sort { |x, y| y <=> x }) == List[1,2,3]