Small introductory post about ARC/ORC in Nim.

[Araq]

`Isolated[T]` has been implemented but now we need a channel implementation 
that works with it... And yeah, if your worker thread can "steal" subgraphs and 
return them back afterwards via moves it is a solution to your problem. If not, 
you need to use atomic refcounts which are coming to fusion... Eventually.