Content packs indices auto build + WorldGenerator fix

src/content/ContentPack.cpp

@@ -10,6 +10,7 @@ namespace fs = std::filesystem;
 
 const std::string ContentPack::PACKAGE_FILENAME = "package.json";
 const std::string ContentPack::CONTENT_FILENAME = "content.json";
+const fs::path ContentPack::BLOCKS_FOLDER = "blocks";
 
 contentpack_error::contentpack_error(
     std::string packId,