[Feature Request] Have a symmetric MarshalJSON and UnmarshalJSON for all API types

[spacedragon]

🚀 Feature Request Description

Types should have symmetric MarshalJSON & UnmarshalJSON

Motivation

The following code should work, but it doesn't because the Transaction doesn't have a MarshalJSON which produce the JSON that can be Unmarshal

tx1 := ...  
jsonBytes, _ = json.Marshal(tx1)

err := json.Unmarshal(jsonBytes, &tx2)  // may err

Pitch

Describe the solution you would like
The MarshalJSON should be defined too.