Publish versions 'patch', 'minor' and 'major'

* `npub publish patch|minor|major` will not auto increment the version.
* `npub publish made.up.version` will now fail semver validation
* updates npub's own publish tasks in the `Makefile`
If invalid, this returns `null`. Later on, it will be caught by a check that will show a message saying that a version is required.

Can we add an error message here instead? I'd rather the error message say that the version entered is invalid.