Alpstein/route-me — pull request #5 by incanus (2011-12-22 00:30:08+00:00)
Title: parallel fetching & compositing of remote tile images

This adds parallelization of the multi-image fetches for web tile sources. They are fetched in a dispatch group, with a configurable number of retries each (defaults to 3) and a configurable wait time for the whole group to finish (default of 2 seconds). Then all successful images are composited using the original routine before the final image is returned.