[phobos] getenv, setenv and unsetenv implemented for Windows

[Walter Bright]

Lars Tandle Kyllingstad wrote:
> Today, I noticed that the std.process functions setenv() and unsetenv()
> only have POSIX implementations.  So I wrote Windows implementations for
> them:
>
> http://github.com/kyllingstad/ltk/blob/master/ltk/system.d
>
> You'll also note a new Windows implementation of getEnv() and a new
> function allEnv().
>   

Great!

> Seeing as this is my first foray into Windows API land ever, I thought
> I'd post it here before incorporating anything into Phobos.  Please
> comment -- in particular I'm curious about whether it is correct to use
> the UTF-16 functions.
>
>   

It is correct to use the "A" functions for Win9x, and the "W" functions 
for all the other Windows versions. To see how to accomplish this, see 
std\file.d and grep for useWfuncs.