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 ;)

Lib/lib-tk/Tkdnd.py

@@ -277,7 +277,7 @@ class Tester:
         return self
 
     def dnd_enter(self, source, event):
-        self.canvas.focus_set() # Show higlight border
+        self.canvas.focus_set() # Show highlight border
         x, y = source.where(self.canvas, event)
         x1, y1, x2, y2 = source.canvas.bbox(source.id)
         dx, dy = x2-x1, y2-y1