Atomic Ref Counting

[dsimcha]

== Quote from Andrei Alexandrescu (SeeWebsiteForEmail at erdani.org)'s
> Thanks for taking the time to build a credibla baseline. A lot of this
> depends on the perspective. We're looking at a 2.9x slowdown after all.

Right, but this isn't a 2.9x slowdown in real world code.  It's a 2.9x slowdown in
a synthetic benchmark that does nothing but increment and decrement reference
counts.  Real world code would likely have a loop body and stuff.  That's why I
consider it minor.