This gives mmap() on Windows the ability to create read-only, write-
through and copy-on-write mmaps. A new keyword argument is introduced
because the mmap() signatures diverged between Windows and Unix, so
while they (now) both support this functionality, there wasn't a way to
spell it in a common way without introducing a new spelling gimmick.
The old spellings are still accepted, so there isn't a backward-
compatibility issue here.
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).