Structure

This is less pull request, but rather a question. I would be happy to make my hands dirty with go and your project looks awesome to start with :)

What I intended to do is:

- decouple previewdocs.go into a bunch of functions, leaving only `main` there
- put all related code to `/src` folder (or something)
- add unit test for each function (if applicable)

I found that a bit awkward with go to do that. Simply by moving files into `/src` would break a build, I also didn't like that test files supposed to remain in same folder as code.

I've checked out few `go` projects and can see that `plain` source organisation is considered to be fine? Is that true, are ther any guidlines? Does it make sense if we are talking about go?