Add TimeSliderChoropleth stroke colour/width/opacity argument (#1838)

* added color, width and opacity customization

* formatted code

folium/plugins/time_slider_choropleth.py

@@ -133,9 +133,10 @@ class TimeSliderChoropleth(JSCSSMixin, Layer):
  $("#slider_{{ this.get_name() }}").show();
 
  d3.selectAll('path')
- .attr('stroke', 'white')
- .attr('stroke-width', 0.8)
+ .attr('stroke', '{{ this.stroke_color }}')
+ .attr('stroke-width', {{ this.stroke_width }})
  .attr('stroke-dasharray', '5,5')
+ .attr('stroke-opacity', {{ this.stroke_opacity }})
  .attr('fill-opacity', 0);
 
  fill_map();
@@ -166,11 +167,18 @@ def __init__(
  control=True,
  show=True,
  init_timestamp=0,
+ stroke_opacity=1,
+ stroke_width=0.8,
+ stroke_color="#FFFFFF",
  ):
  super().__init__(name=name, overlay=overlay, control=control, show=show)
  self.data = GeoJson.process_data(GeoJson({}), data)
  self.highlight = highlight
 
+ self.stroke_opacity = stroke_opacity
+ self.stroke_width = stroke_width
+ self.stroke_color = stroke_color
+
  if not isinstance(styledict, dict):
  raise ValueError(
  f"styledict must be a dictionary, got {styledict!r}"