Alpstein/route-me — pull request #25 by incanus (2012-02-22 01:20:11+00:00)
Title: better tile notifications on main queue & with tile reference hashes

This does three things:

1. This adds proper tile request/retrieve notifications for the MBTiles tile source (despite being local, it's still nice to know that tiles are loading).

1. This makes sure to post all notifications on the main thread, since tile image fetches don't always happen there due to `CATiledLayer`.

1. This posts an `NSNumber` object with a tile's key to indicate which tile is being referred to, rather than `nil` for all notifications.