* Improve the hash function to increase the chance that distinct sets will
have distinct xor'd hash totals.
* Use PyDict_Merge where possible (it is faster than an equivalent iter/set
pair).
* Don't rebuild dictionaries where the input already has one.
* Install the unittests, docs, newsitem, include file, and makefile update.
* Exercise the new functions whereever sets.py was being used.
Includes the docs for libfuncs.tex. Separate docs for the types are
forthcoming.
Raymond Hettinger
Guido van Rossum