text: Title: [BUG] shift_auto_shape_color config for semantic segmentation on Windows 10 not working
  Body: - OS: Windows 10
  - Labelme Version: 4.2.10
  
  The "shift_auto_shape_color" config doesn't seem to be working. I'm on Windows 10 and am running this command (based on the semantic segmentation example):
  
  ```
  labelme data_annotated --labels labels.txt --nodata --validatelabel exact --config                               
   '{shift_auto_shape_color: -2}'
  ```
  
  I end up getting this error:
  ```
  usage: labelme [-h] [--version] [--reset-config]
                 [--logger-level {debug,info,warning,fatal,error}]
                 [--output OUTPUT] [--config CONFIG] [--nodata] [--autosave]
                 [--nosortlabels] [--flags FLAGS] [--labelflags LABEL_FLAGS]
                 [--labels LABELS] [--validatelabel {exact,instance}]
                 [--keep-prev] [--epsilon EPSILON]
                 [filename]
  labelme: error: unrecognized arguments: -2}'
  ```
  
  Is this a bug or something wrong with how I'm using it? Thanks.