- Remove cruft left over from previous RPC backend implementation in

- Remove cruft left over from previous RPC backend implementation in
  the apartment structure.
- Don't pass an IPID by value for proxy_manager_create_ifproxy.
- Disable more of RPC_UnregisterInterface to prevent the RPC runtime
  using freed memory.
- Rename various external RPC backend functions so that they all have
  the same "RPC_" prefix.
- Reduce the timeout of the function that connects to a local server
  to 30s, like native.