collections: Import independent defaultdict and deque modules into namespace.

collections/collections/__init__.py

@@ -3,3 +3,11 @@
 # CPython implementation brings in metaclasses and other bloat.
 # This is going to be just import-all for other modules in a namespace package
 from _collections import *
+try:
+    from .defaultdict import defaultdict
+except ImportError:
+    pass
+try:
+    from .deque import deque
+except ImportError:
+    pass