func backupGame(gridDir string, game *Game, artStyleExtensions []string) error {
	if game.CleanImageBytes != nil {
		return ioutil.WriteFile(getBackupPath(gridDir, game, artStyleExtensions), game.CleanImageBytes, 0666)
	}
	return nil
}
BackupGame if a game has a custom image, backs it up by appending "(original)" to the
file name.
package main
import (
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"unicode"
)