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/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 02d1b0d..12c5be4 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -3198,7 +3198,7 @@
     if (v == NULL)
 	goto onError;
 
-    /* Shortcut for emtpy or interned objects */
+    /* Shortcut for empty or interned objects */
     if (v == u) {
 	Py_DECREF(u);
 	Py_DECREF(v);
@@ -3385,7 +3385,7 @@
     if (!PyArg_ParseTuple(args, "|i:expandtabs", &tabsize))
 	return NULL;
 
-    /* First pass: determine size of ouput string */
+    /* First pass: determine size of output string */
     i = j = 0;
     e = self->str + self->length;
     for (p = self->str; p < e; p++)