Scala Clippy Versions Save

A constant has been added for common non-exhaustive-match warning pattern, you can now use:

    import com.softwaremill.clippy.ClippySbtPlugin.WarningPatterns._
    // ...
    settings(
      clippyFatalWarnings ++= List(
        NonExhaustiveMatch,
        ".*\\[wartremover:.*\\].*[\\s\\S]*"
      )
    )

Added support for fatal warnings, a new setting can be now set:

    settings(
      clippyFatalWarnings ++= List(
        "match may not be exhaustive[\\s\\S]*" // regular expression
      )
    )