- App takes POST report on /api/report
- Probe publishes to configured target(s)
- Name resolution happens on probe-side
- There's no longer an xfer.ProbePort
- xfer.Collector responsibility is reduced
- Fixes to remaining experimental components.
- rm experimental/bridge: it's not being used, and by changing the
  app/probe comm model, it would require a complete refactor anyway. We
  can easily rebuild it when we need to. It will even be much simpler.
- rm experimental/graphviz: it's broken for some time anyway, and we
  don't really need to play around with it as a rendering option
  anymore.
- rm experimental/oneshot: we never use this anymore.