make use external sumkdft_workers

Author: yomichi

src/dcore/sumkdft_workers/mpi_main.py

@@ -14,11 +14,20 @@
         args = parser.parse_args()
 
         # Runner class
-        m = importlib.import_module('dcore.sumkdft_workers.all_workers')
-        cls = getattr(m, args.runner_cls)
+        m_cls = args.runner_cls.split('.')
+        if len(m_cls) == 1:
+            m = importlib.import_module('dcore.sumkdft_workers.all_workers')
+            cls = getattr(m, args.runner_cls)
+        else:
+            m = importlib.import_module('.'.join(m_cls[:-1]))
+            cls = getattr(m, m_cls[-1])
         runner = cls(args.model_hdf5_file, args.input_file, args.output_file)
         runner.run()
-
+    except ImportError as e:
+        print("Import error:", e)
+        import traceback
+        traceback.print_exc()
+        sys.exit(1)
 
     except Exception as e:
         print("Unexpected error:", e)