add none sort_type about feh HOT 2 CLOSED

diff --git a/src/options.c b/src/options.c
index d3524f7..80f13b6 100644
--- a/src/options.c
+++ b/src/options.c
@@ -537,6 +537,8 @@ static void feh_parse_option_array(int argc, char **argv, int finalrun)
                case OPTION_sort:
                        if (!strcasecmp(optarg, "name"))
                                opt.sort = SORT_NAME;
+                       else if (!strcasecmp(optarg, "none"))
+                               opt.sort = SORT_NONE;
                        else if (!strcasecmp(optarg, "filename"))
                                opt.sort = SORT_FILENAME;
                        else if (!strcasecmp(optarg, "dirname"))