Also embed evmc_status_code to computation.error, and make
the tracer produce cleaner output. No more "Revert opcode executed"
error message. We can distinguish error code between REVERT
and FAILURE in a more cleaner way.
* Fix EVM tracer crash bug when serializing nil stack
* Fix t8n tracer doc
add following description to reflect new functionality
`stdout` - into the stdout output.
`stderr` - into the stderr output.
<file> - into the file <file>-<txIndex>.jsonl.
none - output.basedir/trace-<txIndex>-<txhash>.jsonl.