Cleanup; pure Python 3 metaclass usage.

Author: amcgregor

marrow/schema/declarative.py

@@ -10,8 +10,6 @@
 from .meta import Element
 
 
-# ## Class Definitions
-
 class Container(Element):
 	"""The underlying machinery for handling class instantiation for schema elements whose primary purpose is
 	containing other schema elements, i.e. Document, Record, CompoundWidget, etc.

marrow/schema/meta.py

@@ -112,3 +112,6 @@ def __call__(meta, *args, **kw):
 
 
 Element = ElementMeta("Element", (object, ), dict())
+
+class Element(metaclass=ElementMeta):
+	pass