PR your viewer and unittest contributions?

[0joshuaolson1]

I see some changes that might be good for OpenVDB in general, although the codebase is usually consistent (with some exceptions) about using *_t types and size_t as per code guidelines.

[caron]

I haven't done PR yet because I haven't tested my build on Linux and I haven't got the CLA done yet. I did suggest a fix to the unittest already and it was addressed on their end.

Let's keep this open as a reminder to get that done