Telemetry

In-progress work. Please comment & point out issues.

@fractalcat @afcowie @christian-marie 

See also https://github.com/anchor/vaultaire/pull/63
I personally tend to do these things as

```
    | WriterPointsSimple
    | WriterPointsExtended
```

which presumably is a hangover from my days as a Java developer where completion spaces were an important aspect of making nice with the IDE. Still something to mull over as you're looking to enumerate names.