Fix path to default data file

src/sphere/np_sphere.cpp

@@ -21,7 +21,7 @@ extern void sphere(string config_file, string data_file, string output_path);
  */
 int main(int argc, char **argv) {
 	string config_file = "../../test_data/sphere/DEDFB";
-	string data_file = "../../test_data/sphere/DCLU";
+	string data_file = "../../test_data/sphere/DSPH";
 	string output_path = ".";
 	if (argc == 4) {
 		config_file = string(argv[1]);