memory-mapped files

[Walter Bright]

Andrei Alexandrescu wrote:
> Nice advice on madvise, didn't know about it. Just in case it might be 
> useful to someone, trying madvise with any of the four possible policies 
> did not yield any noticeable change in timing for my particular test.

If you can build 4 windows executables, I can time them on my machine, 
and we can see if windows behaves differently.