#27364: fix "incorrect" uses of escape character in the stdlib.

And most of the tools.

Patch by Emanual Barry, reviewed by me, Serhiy Storchaka, and
Martin Panter.
diff --git a/Tools/demo/ss1.py b/Tools/demo/ss1.py
index c51f041..bf88820 100755
--- a/Tools/demo/ss1.py
+++ b/Tools/demo/ss1.py
@@ -413,7 +413,7 @@
 
     def renumber(self, x1, y1, x2, y2, dx, dy):
         out = []
-        for part in re.split('(\w+)', self.formula):
+        for part in re.split(r'(\w+)', self.formula):
             m = re.match('^([A-Z]+)([1-9][0-9]*)$', part)
             if m is not None:
                 sx, sy = m.groups()