Inventory and lighting improved, now to get ready for going down a level and that's most of the game loop working.

inventory.hpp

@@ -22,6 +22,8 @@ namespace components {
 
     bool decrease(size_t at, int count);
 
+    bool has_item(size_t at);
+
     InventoryItem& get(size_t at);
 
     int item_index(std::string id);