fix linter warnings and add GH lint workflow (#1074)

name: golangci-lint

on:

  workflow_dispatch:

  pull_request:

permissions:

  contents: read

  pull-requests: read

jobs:

  golangci:

    name: lint

    runs-on: ubuntu-latest

    steps:

      - uses: actions/checkout@v3

      - uses: actions/setup-go@v4

        with:

          go-version: "stable"

          cache: false

      - name: golangci-lint

        uses: golangci/golangci-lint-action@v3

        with:

          version: v1.54

          only-new-issues: true

          args: --timeout=10m

run:

  # Enables skipping of directories:

  # - vendor$, third_party$, testdata$, examples$, Godeps$, builtin$

  skip-dirs-use-default: true

  skip-dirs:

    - internal/gopher-lua

    - internal/cronexpr

linters:

  enable:

    - gofmt

linters-settings:

  gofmt:

    simplify: false

  errcheck:

    ignore: cleanup

The format is based on [keep a changelog](http://keepachangelog.com) and this project uses [semantic versioning](http://semver.org).

## [Unreleased]

### Fixed

- Fixed multiple issues found by linter.

### [3.17.1] - 2023-08-23

### Added

//	}

//

// will create the following flags

//

//	-dbname string

//	      dbname

//	-interval int

// duplication in flag names (in the flattened case it's more likely to happen

// unless the caller make due dilligence to create the struct properly), it panics.

//

//

// Note that not all types can have command line flags created for. map, channel

// and function type will not defien a flag corresponding to the field. Pointer

// types are properly handled and slice type will create multi-value command

	sl.Delete(Int(888))

	sl.Delete(Int(1000))

	expect = []Int{Int(-999), Int(-888), Int(1), Int(3), Int(999)}

	if sl.Front().Value.(Int) != -999 {

		t.Fatal()

	}

	}

}

// nolint:unused

func output(sl *SkipList) {

	var x *Element

	for i := 0; i < SKIPLIST_MAXLEVEL; i++ {