fixed return value when invoking software with help flag

src/main.cc

@@ -19,5 +19,4 @@ int main(int ac, char** av)
 	ImageManipulator image_process{input_file, output_file, iterations};
 	image_process.exec_method(method, controlled_size);
 	image_process.write_file();
-	return 0;
 }

src/parseargs.cc

@@ -43,7 +43,7 @@ void processFilenames(po::variables_map const& vm,
 	po::notify(vm);
 	if (vm.count("help") || !vm.count("input")) {
 		std::cout << desc << "\n";
-		std::exit(1);
+		std::exit(!vm.count("help"));
 	}
 
 	auto const input_path = vm["input"].as<path>();