freenet.node.fcp.FCPPluginMessage: Parse "Success" field in plugin messages
- This is mainly needed for the planned synchronous send() functions in FCPPluginClient. Because synchronous operations are blocking, we need the remote partner to tell us when the send() function can stop blocking and return. Thus, we need to send a reply message to every (non-reply) message to indicate that the call is finished. To indicate that the message is a reply, the "Success" field is used.
- Bonus feature: Because we'll be sending replies anyway, we can also ship the information of whether the operation succeeded or not - so the success field is boolean. It will probably also be useful to allow shipping of an error code and error message, the following commit will add a FIXME for that.
- Bonus feature: The whole of this makes the stuff more similar to standard "remote procedure call" operations. Each non-reply message is a procedure call, each reply is the procedure result, and they only happen in pairs.
- This new FCP field is not yet added to the official documentation of FCP (= the freenet Wiki). I will do that as soon as the code is merged into mainline.