Add #to_ary to Diff::LCS::Change and Diff::LCS::ContextChange

It would be quite handy if you could write as follows:

```ruby
Diff::LCS.sdiff(a, b).each do |action, (old_position, old_element), (new_position, new_element)|
  case action
  when '!'
    # replace
  when '-'
    # delete
  when '+'
    # insert
  end
end
```

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/diff/lcs/change.rb b/lib/diff/lcs/change.rb
index 9229069..8dae83b 100644
--- a/lib/diff/lcs/change.rb
+++ b/lib/diff/lcs/change.rb
@@ -41,6 +41,8 @@ class Diff::LCS::Change
     [ @action, @position, @element ]
   end
 
+  alias to_ary to_a
+
   def self.from_a(arr)
     arr = arr.flatten(1)
     case arr.size
@@ -132,6 +134,8 @@ class Diff::LCS::ContextChange < Diff::LCS::Change
     ]
   end
 
+  alias to_ary to_a
+
   def inspect(*args)
     to_a.inspect
   end