Fix the broken PDF links, really this time!

Appending a junk char to the end doesn't quite do it, or doesn't seem to at
any rate.  Instead, pad the page numbers to always be 3 charaters wide, with
leading zeros.
diff --git a/Doc/tools/toc2bkm.py b/Doc/tools/toc2bkm.py
index 0d22fb1..ed78f36 100755
--- a/Doc/tools/toc2bkm.py
+++ b/Doc/tools/toc2bkm.py
@@ -101,7 +101,7 @@
 
 def write_toc_entry(entry, fp, layer):
     stype, snum, title, pageno, toc = entry
-    s = "\\pdfoutline goto name{page.%dx}" % pageno
+    s = "\\pdfoutline goto name{page%03d}" % pageno
     if toc:
 	s = "%s count -%d" % (s, len(toc))
     if snum: