* Make iface::read() return a bit more generic address (sockaddr).
* Add is_unicast() and is_multicast() to address.
* Set default config path to "/etc/ndppd.conf".
* Silently ignore solicit messages with bad saddr and/or daddr.
* Add '-d' to "daemonize". Will also enable syslogging.
* Fix a couple of bugs in 'session'.
* Clean up 'log', and use LOG_* macros instead.
* Add syslog(bool) to 'log' to enable/disable the use of syslog.
- Clean up some junk code that was left over.
- Replace ptr<> with strong_ptr<> and weak_ptr<> to easier distinguish
between weak and strong pointers.
- Fix a couple of bugs.