Move some of the public interface to the private side. This includes two structures
 - netloc_lookup_table_entry_t
 - netloc_dt_lookup_table_t
The structures above should be used as opaque structures.

Also start improving the doxygen.
* Add a --help option to netloc_ib_extract_dats
* Make an "xnc" alias for "opendaylight" since they use the same mechanism at the moment.
* Add a bunch of documentation
  * Document the user facing API
  * Document the tools
* Add some examples
  * netloc_hello : Simple netloc only program to get information about a specific node
  * netloc_nodes : List all of the nodes in a specific network
  * netloc_all   : List all of the nodes in all of the networks