Updated internals of Route object in core

- Renamed "host" attribute to "address"
- Only accept IPv4/IPv6 addresses for "address" attribute
- Do input checking when the attribute (property) is writen to,
  not when the underlying C struct is encoded

darcs-hash:20090227145441-58103-8b05e03055665d18c9d248b03fde5f061833cd4c