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/os.py b/Lib/os.py
index c7a3cc5..8e1e4f0 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -218,7 +218,7 @@
 
     Execute the executable file (which is searched for along $PATH)
     with argument list args, replacing the current process.
-    args may be a list or tupe of strings. """
+    args may be a list or tuple of strings. """
     _execvpe(file, args)
 
 def execvpe(file, args, env):
@@ -227,7 +227,7 @@
     Execute the executable file (which is searched for along $PATH)
     with argument list args and environment env , replacing the
     current process.
-    args may be a list or tupe of strings. """    
+    args may be a list or tuple of strings. """    
     _execvpe(file, args, env)
 
 _notfound = None