v2.1.5 release

[Leif Hedstrom]

Hi all,

I started working on TS-590 ("changing APIs to have consistent and 
reasonable return values / types"), and I've come to realize this is a 
beast. It'll probably take me another 1-2 weeks at least to complete. 
So, I think we should go ahead and make a v2.1.5 release with what we 
got. And then aim for another (hopefully last) API breaking release for 
v2.1.6.

Fwiw, there's a large amount of changes and fixes already on trunk, so 
it's very reasonable to make a v2.1.5 release to get that out.

Thoughts?

-- leif