2 Column Text plain text or markdown editor? I'm looking for a text editor of some kind where it's split down the middle when editing 2 separate files.  

I'm trying to translate some text and it would be helpful if I could have English and its meaning on 1 side and Spanish on the other.

Is there anything like this for OS X?
There is also Emacs where you can split a window horizontally:



vertically:



or in a more complicated fashion: