Describe const/mutable interactions and give rationale for no

reverse_iterator_pair_generator.


[SVN r9285]

libs/utility

@@ -1 +1 @@
-Subproject commit d9d58ea66e34c6971e849c59b5b811e74c0d119a
+Subproject commit 168012b46572ed0ef75908dc1812a82ba82b99a7