text: Title: Feature request: option to remove 'E', 'W', 'N', 'S' from axis labels
  Body: ### Description
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  I would like to be able to format my axis labels so that there is no N/S/E/W after the label. 
  
  Is this possible? It seems like a simple option could be added to the Longitude/Latitude formatters. 
  
  In Basemap there was an option for labelstyle="+/-" that could do exactly this. 
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