Add a C API to Neuropod

[vkuzmin-uber]

Feature

C API

We don't expect that somebody is using C API directly. This will be used by future CGo API mostly.

Connected to https://github.com/uber/neuropod/issues/294

Describe the solution you'd like

Design is inspired by the TensorFlow C API and Uber CGO package that includes Bridge C/C++ bridge. Namely: Internal C Headers Public C Headers C/C++ implementation of public and internal headers.

[VivekPanyam]

We don't expect that somebody is using C API directly. This will be used by future CGo API mostly.

I don't think this is accurate. We should build this API in a way where it provides a robust easy-to-use interface to use Neuropod from C (independent of the Go API)

[vkuzmin-uber]

We don't expect that somebody is using C API directly. This will be used by future CGo API mostly.

I don't think this is accurate. We should build this API in a way where it provides a robust easy-to-use interface to use Neuropod from C (independent of the Go API)

Agree, just wanted to highlight that CGO is going to be a first user really, not only.