Desingleton creator (#527)

* De-singleton creator and wrapper and update docstring

* Sneak a fix for 522 while we're here

pyiron_workflow/create.py

@@ -8,25 +8,18 @@
 
 from executorlib import Executor as ExecutorlibExecutor
 from pyiron_snippets.dotdict import DotDict
-from pyiron_snippets.singleton import Singleton
 
 from pyiron_workflow.executors import CloudpickleProcessPoolExecutor
 from pyiron_workflow.nodes.function import as_function_node, function_node
 
 
-class Creator(metaclass=Singleton):
+class Creator:
     """
     A container class for providing access to various workflow objects.
-    Gives access to various workflow tools and, by virtue of being a singleton, makes them
-    available to all composite nodes holding a creator.
+    Gives access to various workflow tools.
 
     In addition to node objects, the creator also provides workflow-compliant executors
     for parallel processing.
-    This includes a very simple in-house executor that is useful for learning, but also
-    choices from the :mod:`executorlib` packages.
-    Some :mod:`executorlib` executors may not be available on your machine (e.g. flux-
-    and/or slurm-based executors), in which case these attributes will return `None`
-    instead.
     """
 
     def __init__(self):
@@ -97,10 +90,9 @@ def transformer(self):
                 ]
             }
         )
-        return super().__dir__() + list(self._package_access.keys())
 
 
-class Wrappers(metaclass=Singleton):
+class Wrappers:
     """
     A container class giving access to the decorators that transform functions to nodes.
     """