Access interface

[ghost]

Implement interface function for accessing data based on 'parson' library

[sheredom]

So I'm gonna be upfront here - I really don't like this MR:

• It copies and pastes code from a different repository with a totally different license.
• It uses string.h, math.h headers that I don't think we need (and have compatibility issues cross platform).
• It introduces helper functions that I don't think we need.

Also, when filing an MR it'd really help me as the owner of the code if:

• You gave a verbose description of what you want the code to do differently.
• Why you have changed the code.
• What are your motivating use-cases.

To save you the time from doing anymore work on this, I won't be accepting functionality to this repository just because a competing library 'parson' has them (and honestly I don't even like what 'parson' did there!)