- patch #1600346 submitted by Tomer Filiba

- Renamed nb_nonzero slots to nb_bool
- Renamed __nonzero__ methods to __bool__
- update core, lib, docs, and tests to match

Lib/test/test_iter.py

@@ -327,10 +327,10 @@ class TestCase(unittest.TestCase):
         class Boolean:
             def __init__(self, truth):
                 self.truth = truth
-            def __nonzero__(self):
+            def __bool__(self):
                 return self.truth
-        bTrue = Boolean(1)
-        bFalse = Boolean(0)
+        bTrue = Boolean(True)
+        bFalse = Boolean(False)
 
         class Seq:
             def __init__(self, *args):