Module to work with environment variables

[FreeSlave]

As I remember there was module to work with environment variables 
in standard library. But now I can't find it. Was it removed or 
merged with some other module?

Another question: I see some of modules are "considered out-dated 
and not up to Phobos' current standards". Can I make attempt to 
rewrite them so new versions will be included in standard 
library? But what are "Phobos' current standards"? Are they 
described somewhere?