Auto mkdir output parents

Author: kburns

dedalus/core/evaluator.py

@@ -447,7 +447,7 @@ def __init__(self, base_path, *args, max_writes=None, mode=None, **kw):
         # Create output folder
         with Sync(comm):
             if comm.rank == 0:
-                base_path.mkdir(exist_ok=True)
+                base_path.mkdir(exist_ok=True, parents=True)
 
     def add_task(self, *args, **kw):
         super().add_task(*args, **kw)