Thanks to Christof Schulze for noticing the problem.

The previous choice was not unique in the presence of multiple next hops.

The absolute path to the socket can be passed to the -g/-G command line
options, or to the new local-path/local-path-readwrite config file
directives.
Signed-off-by: Julien Cristau <jcristau@debian.org>

Thanks to Dave Taht and Julien Cristau for pointing out the issue.

It's been broken for ages, nobody noticed.

Two main modifications:
  - source-specific routes are putted in front of the RIB,
  - route_stream now allows traversing all routes, all installed routes,
    or source-specific installed routes.

This fixes compilation under musl.

It also update the route's id.

Thanks to Julien Cristau.

This was requested by people who want to parse the local socket output
using sed/awk scripts.

Use the hostname instead of "alamakota" when announcing the router
on the local interface.  It would make it possible for visualisation
tools, such as babelweb, to display a meaningful name automatically.