add DataPack encode and decode rpc message

[noneghost]

A DataPack API is added to implement the encoding and decoding logic of messages. The default encode and decode logic is still JSON, and when the user wants to extend, pass in the user-implemented DataPack class instance when instantiating on the server or client.

export interface DataPack {
    encode(value: any): any;
    decode(value: any): any;
}

export class DefaultDataPack implements DataPack
{
    encode(value: any)
    {
        return JSON.stringify(value)
    }

    decode(value: any)
    {
        return JSON.parse(value)
    }
}

[mkozjak]

Looks great. Just need to sort out these first few lines in API.md that are modified for some reason.

[mkozjak]

Looks great! Just minor changes on API.md needed.

[noneghost]

Looks great! Just minor changes on API.md needed.

Are there any other questions with the API documentation?

[mkozjak]

Looks good! Thanks!