cleanup todo comments, tweak default board for incrementer level

src/marble_engine/grid.rs

@@ -255,7 +255,7 @@ impl Grid {
 					let texture = textures.get(texname);
 					draw_scaled_texture(d, texture, px, py, scale);
 					#[cfg(debug_assertions)]
-					// TODO: some in-game option to show power direction
+					// todo some in-game option to show power direction
 					if let Tile::Powerable(_, state) = &tile {
 						for dir in Direction::ALL {
 							if state.get_dir(dir) {