Merge branch 'deal-in-map-coords' into shroud-lazy-update
Vastly improve shroud rendering performance.

Changes in the shroud are now tracked. If a cell changes it will mark itself and its neighbors as dirty. During the render phase all dirty cells will have their vertices calculated and cached. If a cell is not dirty, the pre-calculated vertices are retrieved from cache. Then the sprite renderer is provided the sprite and the pre-calculated vertices to draw.

This prevents constant recalculation of vertices for the shroud in the render phase, requiring instead only dirty cells in the visible area. The update phase is reduced to a practical noop, instead incurring the cost only of changed cells each frame, rather than checking the visible area.