Skogul v0.15.2

Release date: 2022-05-09

Adds plumbing for modular encoding, but more importantly, an enrichment
updater sender.

The sender "enrichmentupdater" and the corresponding changes to the
enrichment transformer will allow on-line updates to the enrichment
database using regular Skogul pipelines. You can load a JSON file at
start-up with an initial database of enrichment, then update that database
on the fly over an HTTP interface for example, if you set up a
receiver-pipeline that ends in an enrichment updater.

Both the enrichment updater and the enrichment transformer is STILL
experimental, but I'm feeling good about them, and they will be a major
addition to medium to large-scale Skogul deployments.

PS: I botched the NEWS in v0.15.1 so let's go lucky v0.15.2.