LEL can now do hit detection on squares.

lel.hpp

@@ -2,6 +2,7 @@
 #include <string>
 #include <unordered_map>
 #include <functional>
+#include <optional>
 
 namespace lel {
   struct Cell {
@@ -39,6 +40,7 @@ namespace lel {
     void reset();
     bool parse(std::string input);
     void finalize();
+    std::optional<std::string> hit(int x, int y);
   };
 
   Cell center(int width, int height, Cell &parent);