New transaction formats for sharding


Here is a proposed new transaction format.

    version_num,  # Transaction format version, 0 for now
    chain_id,     # 1 for ETH, 3 for ropsten...
    shard_id,     # The ID of the shard the tx goes on
    acct,         # The account the tx enters through
    gas,          # Total gas supply
    data          # Tx data

Depending on what is done in Tradeoffs in Account Abstraction Proposals, fields can simply be added on to the end of this as needed.