nix-shell -A nrm for a nrm development environment.
nix-shell -A test for an versioned integration test environment.
nix-build -A <tab> to build a package from the versioned test environment.
nix-shell -A <tab> for other shell options.
nix-build -A <tab> for other build options.

The last merge changed the API visual style to increase readability.

The manual merging was not done in a proper way however, and some of the
changes from its previous merges were reverted. This commit fixes this.

The option accepts a message type and prints the values in the csv
format:
msgtype, time, payload if the --filter option is recognized
msgtype, time otherwise
The print is force-flushed on stdout.
This switches CI to the "refactored" CI identifier at argotests/tests

the gitlab-ci.yml file now points to argotest/gitlab/basic.yml on
master.

This commits simplifies the CI setup for this repository, offloading
all complexity to the "argotest" repository.