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/Demo/sgi/video/OldVcopy.py b/Demo/sgi/video/OldVcopy.py
index 697a51a..0eb1c7f 100755
--- a/Demo/sgi/video/OldVcopy.py
+++ b/Demo/sgi/video/OldVcopy.py
@@ -15,10 +15,10 @@
 	print 'Frame', iframe, ': t =', time
 
 def usage():
-	sys.stderr.write('usage: Vcopy [-t type] [-m treshold] [-a] infile outfile\n')
+	sys.stderr.write('usage: Vcopy [-t type] [-m threshold] [-a] infile outfile\n')
 	sys.stderr.write('-t Convert to other type\n')
 	sys.stderr.write('-a Automatic\n')
-	sys.stderr.write('-m Convert grey to mono with treshold\n')
+	sys.stderr.write('-m Convert grey to mono with threshold\n')
 	sys.stderr.write('-d Convert grey to mono with dithering\n')
 	sys.exit(2)