Add the 'bool' type and its values 'False' and 'True', as described in

PEP 285.  Everything described in the PEP is here, and there is even
some documentation.  I had to fix 12 unit tests; all but one of these
were printing Boolean outcomes that changed from 0/1 to False/True.
(The exception is test_unicode.py, which did a type(x) == type(y)
style comparison.  I could've fixed that with a single line using
issubtype(x, type(y)), but instead chose to be explicit about those
places where a bool is expected.

Still to do: perhaps more documentation; change standard library
modules to return False/True from predicates.

Lib/test/output/test_augassign

@@ -4,14 +4,14 @@ test_augassign
 6
 [1, 2, 3, 4, 1, 2, 3, 4]
 [1, 2, 1, 2, 3]
-1
-1
-1
+True
+True
+True
 11
-1
+True
 12
-1
-1
+True
+True
 13
 __add__ called
 __radd__ called