A bit of late night work designing the little iterators.

lights.hpp

@@ -40,7 +40,7 @@ namespace lighting {
     LightRender(size_t width, size_t height) :
       $width(width),
       $height(height),
-      $lightmap(height, MatrixRow(width, 0)),
+      $lightmap(height, matrix::Row(width, 0)),
       $paths(width, height)
     {}