SF #754014:  list.index() should accept optional start, end arguments

Also, modified UserList.index() to match and expanded the related tests.
diff --git a/Lib/UserList.py b/Lib/UserList.py
index 76cf31f..dd1b927 100644
--- a/Lib/UserList.py
+++ b/Lib/UserList.py
@@ -75,7 +75,7 @@
     def pop(self, i=-1): return self.data.pop(i)
     def remove(self, item): self.data.remove(item)
     def count(self, item): return self.data.count(item)
-    def index(self, item): return self.data.index(item)
+    def index(self, item, *args): return self.data.index(item, *args)
     def reverse(self): self.data.reverse()
     def sort(self, *args): self.data.sort(*args)
     def extend(self, other):