Initial python3 changes

Mostly just updating libraries, removing string encoding/decoding,
fixing some edge cases. No new functionality was added in this
commit.

lib/jaraco/classes/ancestry.py

@@ -0,0 +1,68 @@
+"""
+Routines for obtaining the class names
+of an object and its parent classes.
+"""
+
+from more_itertools import unique_everseen
+
+
+def all_bases(c):
+    """
+    return a tuple of all base classes the class c has as a parent.
+    >>> object in all_bases(list)
+    True
+    """
+    return c.mro()[1:]
+
+
+def all_classes(c):
+    """
+    return a tuple of all classes to which c belongs
+    >>> list in all_classes(list)
+    True
+    """
+    return c.mro()
+
+
+# borrowed from
+# http://code.activestate.com/recipes/576949-find-all-subclasses-of-a-given-class/
+
+
+def iter_subclasses(cls):
+    """
+    Generator over all subclasses of a given class, in depth-first order.
+
+    >>> bool in list(iter_subclasses(int))
+    True
+    >>> class A(object): pass
+    >>> class B(A): pass
+    >>> class C(A): pass
+    >>> class D(B,C): pass
+    >>> class E(D): pass
+    >>>
+    >>> for cls in iter_subclasses(A):
+    ...     print(cls.__name__)
+    B
+    D
+    E
+    C
+    >>> # get ALL classes currently defined
+    >>> res = [cls.__name__ for cls in iter_subclasses(object)]
+    >>> 'type' in res
+    True
+    >>> 'tuple' in res
+    True
+    >>> len(res) > 100
+    True
+    """
+    return unique_everseen(_iter_all_subclasses(cls))
+
+
+def _iter_all_subclasses(cls):
+    try:
+        subs = cls.__subclasses__()
+    except TypeError:  # fails only when cls is type
+        subs = cls.__subclasses__(cls)
+    for sub in subs:
+        yield sub
+        yield from iter_subclasses(sub)