cosmetic
No need for make publish
Missed change of command in usage message
Factor out ask_version and don't exit 1 if it fails
nicer error when there is no version tag
more idiomatic go build time variable setting
avoiding the use of 'sed'
accept lightweight tags
ignore release dir
don't allow lightweight tags after all
Upload the release artefact to a "latest_release" release

We would like to have a stable URL for the most recently released
script, so that we can mention it in the README and people can use it
in update scripts.

Since GitHub's releases/latest URL redirects, and anyway doesn't work
for downloads, we have to create (possibly delete first) a release
tagged "latest_release" and update it.