add 'model-name' item property

src/items/ItemDef.hpp

@@ -35,6 +35,8 @@ struct ItemDef {
     std::string placingBlock = "core:air";
     std::string scriptName = name.substr(name.find(':') + 1);
 
+    std::string modelName = name + ".model";
+
     struct {
         itemid_t id;
         blockid_t placingBlock;