Golang Encoder / Decoder interface

[nikkolasg]

Would it be possible to implement an Encoder and Decoder interface for protobuf so we can use it like others encoding libraries ?
For networking, it would mean a real improvement if we could have something

dec := protobuf.NewDecoder(conn)
dec.Decode(&value)

Instead of having to read all the bytes to a buffer and passing in protobuf.

[nikkolasg]

Linked to #3