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/Modules/md5module.c b/Modules/md5module.c
index 545df2b..e3d5804 100644
--- a/Modules/md5module.c
+++ b/Modules/md5module.c
@@ -145,7 +145,7 @@
 straightforward: use the new() to create an md5 object. You can now\n\
 feed this object with arbitrary strings using the update() method, and\n\
 at any point you can ask it for the digest (a strong kind of 128-bit\n\
-checksum, a.k.a. ``fingerprint'') of the contatenation of the strings\n\
+checksum, a.k.a. ``fingerprint'') of the concatenation of the strings\n\
 fed to it so far using the digest() method.\n\
 \n\
 Functions:\n\