First step in removing the libconfuse dependency.
- Switch from the old 'log' class (ERR/DBG/etc) to a better 'logger' class. Also use LOG_* as defined in syslog.h. - Make it possible to read debug messages even for release. - Add a new argument (-v|--verbose) to 'ndppd' to change verbosity level.
- Change coding style - Switch from own implementation of smart pointers to std::smart_ptr and std::weak_ptr
