Makes a lot more sense

- Renamed interface_* files and classes
- io_service is correctly owned by the correct classes and initialized first
- No more pointer used for sockets to work around the previous bad design

fixes #2257

The InterfaceRemoteClient can then be derivated in an other client: GameRemoteClient, and avoid code duplication.

This makes the data easier to track and free after
they were sent. And it makes sure the buffer stays valid
for all the async_write() process.
It’s also easier to send data without having to bother with
creating a string, parsing everything, etc.

TODO: the reception of that file by the client.

Implement all the connection + auth process. Also fix a leak by correctly deleting the clients that get disconnected.

Do all includes with <> instead of "". We just need to pass the -Isrc/ option to the compiler, or equivalent.

Now we can easily implement a request/answer protocol between the clients
and the server.