Many changes in (mainly) kernel syncers.

- BSD kernel syncer is now self-conscious and can learn alien routes
- important bugfix in BSD kernel syncer (crash after protocol restart)
- many minor changes and bugfixes in kernel syncers and neighbor cache
- direct protocol does not generate host and link local routes
- min_scope check is removed, all routes have SCOPE_UNIVERSE by default
- also fixes some remaining compiler warnings

nest/proto.c

@@ -113,7 +113,6 @@ proto_new(struct proto_config *c, unsigned size)
   p->table = c->table->table;
   p->in_filter = c->in_filter;
   p->out_filter = c->out_filter;
-  p->min_scope = SCOPE_SITE;
   p->hash_key = random_u32();
   c->proto = p;
   return p;