Vote on region allocator

[Jonathan M Davis]

I'm going to have to vote no as well. The most recent changes aren't small and 
haven't been thoroughly reviewed, and from what little review of it there 
_has_ been, I think that it's pretty clear that there are still issues that 
need to be sorted out. The custom allocator scheme is critical to the standard 
library and needs to be solid before we introduce it into Phobos, and it's not 
at all clear that the current API is all that solid. Good progress has been 
made, but I think that it needs more bake time.

- Jonathan M Davis