Build refactoring

[Rémi Bèges]

Simplification of the build process.

Distributions will no longer assembled by gathering files from different folders, which is too complex and obscure for the unfamiliar user.

Instead, distributions will be pre-constructed (each distribution folder will contain a .h/.hpp for interface and .c/.cpp for distribution)

Then, only C core code will be copied into their respective c_api subfolder
A JSON file could be used to list all distributions and make adding a new one easy.