Implement Non-interactive defaults

[evan-forbes]

Summary

Use the non-interactive defaults described in the spec

Details

The spec describes the non-interactive default rules, which allow for commitments to a message to be generated without external info. Please see spec for more detail.

The app will also need to import this functionality, so that it can properly arrange shares while staying within the max square size.

This issue should only be handled after determining square size #454 has been implemented.

Action Items

• Add non-default functionality in celestia-core's (probably around message splitting)
• fix incorrectly generated commitments in the app #53
• import functionality to celestia-app
• the app needs to add the starting location of each message as meta data to SignedTransactionDataPayForMessages
• add non-interactive default psuedo-code to the spec (comment)

blocked by #454

[liamsi]

While at it, we should contribute back to the spec to contain these "Non-interactive defaults" as pseudo-code. The current English description is too difficult to follow and predestined for pseudo-code.

[evan-forbes]

closing in favor of celestiaorg/celestia-app#382