v0.18.1

Not much has changed since the last release, which means things are stabilizing...

Documentation is still missing, errors are still criptic, but I use it every day! (This is why I still mark this release as "pre-release".)

The highlights are using Go 1.17, updating dependencies, refactoring z-run scripts used to build and test z-run itself.

A non-essential, but in my view very interesting feature is embedding the sources within the executable itself. Trully open-source...