Wallet protocol

[arvidn]

• add macros to making it more succinct to define new message types and streamable types
• add all protocol types required for the Wallet Protocol
• add chia protocol wrapper message

This patch set is suitable to be reviewed one commit at a time.

[richardkiss]

Long, but seems pretty straightforward. This is the kind of code that problems will be uncovered as we try it (or via integration tests).

[arvidn]

yes. we won't be using these for a while. I expect to have more tests by then