The new std.process is ready for review

[Lars T. Kyllingstad]

It's been years in the coming, but we finally got it done. :)  
The upshot is that the module has actually seen active use over 
those years, both by yours truly and others, so hopefully the 
worst wrinkles are already ironed out.

Pull request:
https://github.com/D-Programming-Language/phobos/pull/1151

Code:
https://github.com/kyllingstad/phobos/blob/std-process2/std/process2.d

Documentation:
http://www.kyllingen.net/code/std-process2/phobos-prerelease/std_process2.html

I hope we can get it reviewed in time for the next release.  (The 
wiki page indicates that both std.benchmark and std.uni are 
currently being reviewed, but I fail to find any "official" 
review threads on the forum.  Is the wiki just out of date?)

Lars