expose reference count mechanism for Zig code use

[kyle-github]

See the comments in issue #158. If such a mechanism is implemented with underlying reference counting, just expose it in some manner so that Zig code can use it. This may tie into some of the ideas in issue #453 as a "low tech" way of implementing shared/ref counted entities.

[andrewrk]

Let's talk about issues #158 and #453 in those issues.