C-only interface

[arlolra]

To facilitate FFI bindings in other languages.

[arcrose]

As it stands, we're going to create a C API wrapping around the C++ interface. There's a lot of cleanup to do first, but we're going to have a much nicer API.

[chrisballinger]

Awesome! :+1:

Up next... Swift & Rust bindings to the C API