message: Use ternary to simplify overlayColor helper method
diff: @@ -62,12 +62,7 @@ namespace {
  const NAS2D::Color& overlayColor(Tile::Overlay overlay, bool isHighlighted)
  {
  - if (isHighlighted)
  - {
  - return OverlayHighlightColorTable.at(overlay);
  - }
  -
  - return OverlayColorTable.at(overlay);
  + return (isHighlighted ? OverlayHighlightColorTable : OverlayColorTable).at(overlay);
  }
  