Spelling fixes supplied by Rob W. W. Hooft. All these are fixes in either
comments, docstrings or error messages. I fixed two minor things in
test_winreg.py ("didn't" -> "Didn't" and "Didnt" -> "Didn't").

There is a minor style issue involved: Guido seems to have preferred English
grammar (behaviour, honour) in a couple places. This patch changes that to
American, which is the more prominent style in the source. I prefer English
myself, so if English is preferred, I'd be happy to supply a patch myself ;)
diff --git a/Lib/multifile.py b/Lib/multifile.py
index 977b92f..cc8f43c 100644
--- a/Lib/multifile.py
+++ b/Lib/multifile.py
@@ -21,7 +21,7 @@
 The latter sequence may be used recursively at (A).
 It is also allowed to use multiple push()...pop() sequences.
 
-If seekable is given as 0, the class code will not do the bookeeping
+If seekable is given as 0, the class code will not do the bookkeeping
 it normally attempts in order to make seeks relative to the beginning of the
 current file part.  This may be useful when using MultiFile with a non-
 seekable stream object.