This new function returns true if the given address is in the range of
any "private" or "local" networks as defined in RFC1918 (IPv4) or
RFC3484/RFC4193 (IPv6), otherwise they return false.

These ranges are:

   192.168.0.0/16
   172.16.0.0/16
   10.0.0.0/24
   FC00::/7
   FEC0::/10