Proposal: Add more linters to golangci-lint config

[nkryuchkov]

I'd suggest adding more linters to the golangci-lint config. This could help us improve the code quality and detect possible bugs that might be hard to find in the future.

Full linter list: https://github.com/golangci/golangci-lint#supported-linters

Personally, I would add the following ones:

• bodyclose
• dupl
• gocritic
• scopelint
• unconvert