NLSR

Currently, NLSR uses Doxygen only very sparingly, and only on publicly-exposed entities in the source tree. Doxygen is a powerful and structured way to write documentation, not just for APIs, but also for general code structures. Since we can easily toggle what visibility of documentation gets exported, we should write Doxygen documentation for all entities in the source, and generate a developer's version and an API reference version.

I propose that Doxygen comments be written for every non-trivial entity in the source, and those comments should answer the questions: Why is this code entity here? Why does this thing exist? What other entities rely on this one to accomplish their jobs?