Linting, formatting and error wrappers

[lexfrei]

Small improvements:

• Linting
• Formatting
• Errors creating
• fmt removed where possible
• github.com/cockroachdb/errors used as a replacement for deprecated "std" errors

[lexfrei]

It looks like the log.Info() is misused. Probably, we can drop all direct "fmt" imports
Proof.

[lexfrei]

Looks like there are a lot of commented code lines. Do you need them as notes or should they be removed?

[bugfest]

Thanks @lexfrei ! Quite a job here. I do agree to drop commented lines of code if I spot anything interesting that otherwise I forget I'll put a comment

[lexfrei]

"io/ioutil" dropped as deprecated, replaced with os

For now, I think, the main cleanup is done. There are a lot of possible improvements, but the biggest part of simple changes is done.

In this work, I used this golangci-lint config.
You can add it to your repo along with this action. But for now, it will fail.

[bugfest]

"io/ioutil" dropped as deprecated, replaced with os

For now, I think, the main cleanup is done. There are a lot of possible improvements, but the biggest part of simple changes is done.

In this work, I used this golangci-lint config. You can add it to your repo along with this action. But for now, it will fail.

Thanks for the suggestion @lexfrei - I've opened #46 track/implement the action.

Will run the build and merge when it finshes. Thanks for all this work!!