Implement Range#reverse_each

[FnControlOption]

Implementation:

def reverse_each
  raise TypeError, "can't iterate from #{self.end.class}" if self.end.nil?
  return super unless self.end.respond_to?(:pred)
  return enum_for(:reverse_each) { size } unless block_given?
  item = self.end
  item = item.pred if exclude_end?
  while self.begin.nil? || item >= self.begin
    yield item
    item = item.pred
  end
  self
end