#17115,17116: Have modules initialize the __package__ and __loader__
attributes to None.

The long-term goal is for people to be able to rely on these
attributes existing and checking for None to see if they have been
set. Since import itself sets these attributes when a loader does not
the only instances when the attributes are None are from someone
overloading __import__() and not using a loader or someone creating a
module from scratch.

This patch also unifies module initialization. Before you could have
different attributes with default values depending on how the module
object was created. Now the only way to not get the same default set
of attributes is to circumvent initialization by calling
ModuleType.__new__() directly.
diff --git a/Doc/reference/import.rst b/Doc/reference/import.rst
index 4ad4490..9c52435 100644
--- a/Doc/reference/import.rst
+++ b/Doc/reference/import.rst
@@ -423,8 +423,8 @@
  * If the module has a ``__file__`` attribute, this is used as part of the
    module's repr.
 
- * If the module has no ``__file__`` but does have a ``__loader__``, then the
-   loader's repr is used as part of the module's repr.
+ * If the module has no ``__file__`` but does have a ``__loader__`` that is not
+   ``None``, then the loader's repr is used as part of the module's repr.
 
  * Otherwise, just use the module's ``__name__`` in the repr.