- Update InvoiceRequest to include nonce
- Remove ephemeral_public_key from ReturnPaymentRequest
- Update message validation and nonce usage in processes
- Make Abstract more readable
- Update Sender definition and acronym descriptions
- Added comments to ReturnPaymentRequest definition
- Bold ECDH and AES Setup notes and added "(see below)" for reference
- Removed Requestor/Responder definitions
- Seperated ECDH secret point generation and AES-256 (CBC Mode) setup from individual steps (listed twice) and created it's own section
- Added InvoiceRequest Validation section