Fix: change flag -i (which is preserved to `cp`) to --exclude-from

gcp

@@ -636,7 +636,7 @@ class GCP():
             action="store_true", default=False,
             help=_("copy directories recursively")
         )
-        group_cplike.add_argument("-i", "--ignore",
+        group_cplike.add_argument("--exclude-from",
               action="store", default=".gcpignore",
               help=_("file name which holds ignored patterns for each directory (default: .gcpignore)")
         )