test_mmap wrote null bytes into its expected-output file; this caused me to waste an hour tracking down an illusion; repaired it; writing/reading non- printable characters (except \t\r\n) into/outof text-mode files ain't defined x-platform, and at least some Windows text editors do surprising things in their presence. Also added a by-hand "build humber" to the Windows build, in an approximation of Python's inexplicable BUILD-number Unix scheme. I'll try to remember to increment it each time I make a Windows installer available. It's starting at 2, cuz I've put 2 installers out so far (both with BUILD #0).