Complete C interface

[mathiasbourgoin]

Currently include/mammut/mammut.h is only a partial C interface to the mammut C++ code. In particular, it only exposes energy counters and energy measurements fonctions.

Topology, thread and processes management features are missing.

It would be helpful to build bindings to have the whole library exposed.

Thanks :)

[DanieleDeSensi]

Sure, actually it is quite straightforward but a bit time-consuming. At the moment I only added those for energy because I needed them for a python binding :) I'll probably keep adding them a few at a time. If you would like to add some of the missing features I can provide you support.