dumpVar: only available in dev mode
Ideally, I would prefer the usual split per logging level, but that seems to be somewhat complex with `tracing_subscriber`, so this simply switches everything over to stderr, so that some of the experiment commands can write results to stdout.
Keep the flexibility for dev, but in prod drop stdout and restrict the log view to stuff useful to the user.
Ref: #7.
Ref #7.
Adds an additional crate for shared functionality between dtmt and dtmm that doesn't fit in the sdk.