Turn --prefix option around one more time

[silverwind]

So after some research it appears the majority of repos use v prefixes and tooling actually works better with the prefixes. I'm thinking of doing one more breaking change which includes:

• removing --prefix and adding --unprefixed.
• make the tag include a v by default, while excluding it in the tag message.

This would match npm behaviour with the default options and is probably the best way forward.

[silverwind]

Actually, I decided against this. It'd be kind of bad for users having to adopt to another breaking change, and I still prefer 'v'-less tags on my own projects because those are actual semvers.