Versioning in project jigsaw

[villa gogh]

Hi,

I just knew the project jigsaw. I'm inspired by the idea of this project!
As I have struggled in how to shared and build a robust lib system in firm.

I'm new to this project, so had missed much about what has already been
discussed.

When I saw the `Versioning` part of Draft, I'm think: Is it possible to
take http://semver.org/ into consideration?

The version can be enforced into some standards. and may the compatible
problem goes with the version together with some tools like api check,
exports verifier, etc.

THS,

Villa Gao