Optimize http requests - Refactor map.cs

[wilhelmberg]

refs #11

From my point of view some logic should move from Core/Tile.cs to Core/Map.cs that should keep track of:

• tiles needed for current map extent
• threaded tile fetching Optimize http requests - threaded tile fetching #23
• retrying failed tiles Optimize http requests - retrying failed tiles #24
• throttling tile requests Optimize http requests - throttling tile requests #25
• aborting tile requests Optimize http requests - aborting tile requests #26
• caching tiles Optimize http requests - caching tiles #27
• reporting progress of tile loading Optimize http requests - reporting progess of tile loading #28

[wilhelmberg]

To be continued: #46