Wataru Ashihara e91f3ec770 Move Object#dig to Struct#dig ...

This method seems to be mistakenly put into `Object` instead of `Struct`
since it's in `struct.rb` and daf83946b says:

  add #dig to Array,Hash and Struct

2019-02-24 16:59:02 +09:00

..

struct.rb

Move Object#dig to Struct#dig

2019-02-24 16:59:02 +09:00