Enable usage as a normal go module.

[jhchabran]

These changes enable to import codenotify as a go module and to use the now exported Subscribers function to compute subscribers from Go code rather than having to call the binary.

Other than a slight code reorganization to allow that, behavior remains unchanged.

[unknwon]

@jhchabran Saw this PR by chance, are you still working on getting this merged?

[jhchabran]

@unknwon not right now as their is another dependent change before this gets merged, but if you need this for any reason, I can fix it and merge it, you tell me :)

[unknwon]

No rush and keep your pace 👍 I was just checking.

[unknwon]

Haha, checking again on this, I want to use it as normal Go module in another project.