Terms about using twitter's sprites/icons



I would like to use the retweet (the green triangle icon), the favorite and the retweet-favotite icon.
I saw the image resource page but you doesn’t provide those icons:

I also read a similar post and an employee linked these sprites:

So I was wondering if I could use the new favorite/retweet icons from the real sprite or if I have to stick with that sprite.
Also, am I allowed to split the sprite in individual images or will it be considered as forbidden copy or modifications ?