This patch addresses two main issues:
(1) There exist some non-fatal errors in some of the hash algorithms. For
    exmaple, in float_hash and complex_hash a certain part of the value is
	not included in the hash calculation. See Tim's, Guido's, and my
	discussion of this on python-dev in May under the title
	          "fix float_hash and complex_hash for 64-bit *nix"
			  
(2) The hash algorithms that use pointers (e.g. func_hash, code_hash) are
    universally not correct on Win64 (they assume that sizeof(long) ==
	sizeof(void*))

As well, this patch significantly cleans up the hash code. It adds the two
function _Py_HashDouble and _PyHash_VoidPtr that the various hashing routine
are changed to use.

These help maintain the hash function invariant:
	(a==b) => (hash(a)==hash(b)))
I have added Lib/test/test_hash.py and Lib/test/output/test_hash to test this
for some cases.