SC_28 update filter shapes

[ArneDefauw]

• update filter_shapes function
• update _plot_shapes. To plot filtered out shapes, they need to be passed explicitely now. E.g.:

  nas.pl.shapes(  sdata, shapes_layer="segmentation_mask_boundaries", 
             shapes_layer_filtered=[ "filtered_segmentation_mask_boundaries_low_counts", 
                                     "filtered_segmentation_mask_boundaries_segmentation",
                                         ] )