Introduce RangeCircleRenderable.
Split selectable rendering into *Renderables.
Add UISpriteRenderable for screen-space decorations.
Change IPostRenderSelection and IPlaceBuildingDecoration to return renderables.
Change IOrderGenerator.RenderAfterWorld to return Renderables.
Merge pull request #6040 from pchote/more-renderables

Convert RenderAfterWorld to use Renderables.