SwiftLint plugin and shared config.

To add to your SPM, add the following lines to your Package.swift:

In the dependencies section:

    .package(url: "https://github.com/nicolas-christe/swiftlint.git", .upToNextMajor(from: "1.0.0")),

in your targets:

    plugins: [.plugin(name: "swiftlint", package: "swiftlint")])

To update swiftgen binaries

Download the artifactbundle.zip from https://github.com/realm/SwiftLint/releases/. In the pluging package directory run swift package compute-checksum SwiftLintBinary-macos.artifactbundle.zip to compute the checksum. Then update the binaryTarget on the package file