add '--no-colors' command-line option

gallery_dl/__init__.py

@@ -38,6 +38,11 @@ def main():
             except ImportError:
                 import toml
             config.load(args.configs_toml, strict=True, loads=toml.loads)
+        if not args.colors:
+            output.ANSI = False
+            config.set((), "colors", False)
+            if util.WINDOWS:
+                config.set(("output",), "ansi", False)
         if args.filename:
             filename = args.filename
             if filename == "/O":