Experimenting with G-Y-M Tiling

Work has begun on supporting the Google/Yahoo/Microsoft and OpenStreetMap tiling schemes .. also basically the same with slightly different naming patterns. The biggest hurdle will be undoing all the projection specific code in worldKit, to also support Mercator. Any help welcome.

This was triggered by Mike Migurski building tiles from Blue Marble NG, in basically the same scheme.

worldKit can handle the tiles in this test of the Blue Marble S3 tiles. But GeoRSS annotations wouldn't be placed correctly.