TODO: Make updates from AMP changes

[junderw]

lightning/bolts#643

This will break since it requires a new field as MUST.

Major version bump and README explanation will be needed... will look at the timeline of LND c-lightning and eclair to see when we should push this out.

[alexbosworth]

I made some JS methods to parse feature flags and the new payment identifier if that is helpful: https://github.com/alexbosworth/ln-service/blob/master/bolt11/parse_payment_request.js#L191