This PR adds https://github.com/blizzy78/consistent as a new linter. This linter checks that common Go constructs are used consistently.
This linter is similar to go-consistent, but not quite the same. go-consistent uses auto-detection, while this linter must be configured manually. I also believe that this linter checks things more thoroughly than go-consistent, including an extensive test suite which also tests for false positives.
go-consistent has been requested in #288. This PR adds much of the requested functionality.