Revamped concurrency API

[Andrei Alexandrescu]

Occasionally people here ask for ways in which they can help D. One 
thing that would be extremely helpful at this point would be to help 
defining and implementing D's new concurrency API. Unfortunately, 
Bartosz has declined to contribute. That leaves Walter, Sean, Don, and 
participants to this group to do it.

I'm sure you know the three of us are overcommitted, and I'm also sure 
many of you are also in that situation. But if we could somehow focus 
all of the energy and good will in this group to one task of 
extraordinary urgency and importance, that would be awesome.

If anyone has ideas, suggestions, and code to help defining a new 
concurrency API for D, please post.


Andrei