Run all linters per package. It allows unloading package data when it's
processed. It dramatically reduces memory (and CPU because of GC) usage.
Relates: #337
Also do following improvements:
- show proper sublinter name for megacheck sublinters
- refactor and make more simple and robust megacheck
merging/optimizing
- improve handling of unknown linter names in //nolint directives
- minimize diff of our megacheck version from the upstream,
https://github.com/golang/go/issues/29612 blocks usage of the upstream
version
- support the new `stylecheck` linter
- improve tests coverage for megacheck and nolint related cases
- update and use upstream versions of unparam and interfacer instead of forked
ones
- don't use golangci/tools repo anymore
- fix newly found issues after updating linters
Also should be noted that megacheck works much faster and consumes less
memory in the newest release, therefore golangci-lint works noticeably
faster and consumes less memory for large repos.
Relates: #314
1. Rename in a backward compatible way
2. Remove gosec default exclude list because gosec is already disabled
by default.
3. Warn about unmatched linter names in //nolint directives
4. Process linter names in //nolint directives in upper case
5. Disable gosec for golangci-lint in .golangci.yml
