title: expand for MongoDB Scala driver?
body: <p><a href="https://mongodb.github.io/casbah/" rel="nofollow noreferrer">Casbah</a> has an <a href="https://mongodb.github.io/casbah/3.1/scaladoc/index.html#com.mongodb.casbah.commons.MongoDBObject@expand[A](key:String)(implicitevidence$13:com.mongodb.casbah.commons.NotNothing[A],implicitevidence$14:Manifest[A]):Option[A]" rel="nofollow noreferrer">expand</a> function that lets you retrieve nested keys.
  Does the newer <a href="http://mongodb.github.io/mongo-scala-driver/" rel="nofollow noreferrer">MongoDB Scala Driver</a> have this functionality?</p>