After debuting the Retina-ized 15” MacBook Pro four months ago, Apple today took the wraps off the 13” MacBook Pro with Retina display ($1699-$1999). There aren’t a ton of surprises here: the new Pro has a thinner body, super-high resolution 2560 by 1600 screen, and has ditched its spinning hard drive in factor of flash storage. Picture the 15” model shrunk down a bit and you’ve got the idea. It’s clear this merger…