v6.0.0

Use streaming pipeline, support stdin (3c9fe2a)

This makes ditched more useful as a Unix tool, as it can start outputting results as it processes its input.

This is much more memory efficient and we can easily throttle the number of concurrent requests toward the npm registry.

Sadly, loses some things:

• --levels option. Use output from 'npm list --depth' instead
• default sorting. Pipe to sort instead.

The output is also swapped to have the number of days as the first column. This is more practical when piping to sort.

New config options:

• concurrency: the max number of parallel requests to the registry
• registry: the base URL to the npm registry