Override blocks have access to the new object but not the old one

[eturino]

the override blocks receive as both first and second arguments the new object, instead of old_object as first argument as the doc suggests.

https://github.com/amoeba-rb/amoeba/blob/master/lib/amoeba/cloner.rb#L113

    def process_overrides
      amoeba.overrides.each do |block|
        block.call(@new_object, @new_object)
      end
    end

should be

    def process_overrides
      amoeba.overrides.each do |block|
        block.call(@old_object, @new_object)
      end
    end