Allow contracts to be called by name. The key contract_pubkey of the name
is resolved while running the transaction. This has consequences for the
contract call structure (aect_call) that gets a new field with the contract
call identifier. In order to be able to find the call result without doing
name resolution calls are stored relative to the id rather than the contract
pubkey.
NOTE: Names can change at any time (frontrunning is possible!) so only call
contracts by name when you trust the owner of the name!
