Transitioning between world-map board and in-world board

Once we have overworld tiles and can build world-maps, the ability to associate a world-map made with them to the in-world board and a transition (keypress, or perhaps just "zooming out into the clouds") from the game board to the world-map board, centered based on current in-game board location. This is the automatic "top-down" or "orthographic" feature, but where the view is hand-crafted instead of having to solve the hard problem described in the #faq when this feature is requested. The burden is moved to the builder to make a world-map that roughly matches the in-game board