PDD 22 I/O branch landed

[Allison Randal]

Will Coleda wrote:
> 
> Is there a way to swap out the old for new so I could, e.g., test it
> with partcl?

This merge is just for platform testing. I/O is deep in the core, and 
has substantial variation between different platforms (it compiles 
completely different code for Windows and *nix), so I wanted an early 
warning of any problems. Starting up the next branch now, which will 
replace the old subsystem with the new. Languages, etc. can test on this 
branch.

Allison