Polygon:

- Added async methods to polygon.
- The `requests` library is no longer required, with `urllib` being used instead.
- Added the `get_bar_data` function, which returns a dataframe of aggregate data from polygon.
- Opened up the `subscribe` and `unsubscribe` functions

Enhancements:
- Tables will now scroll when the rows exceed table height.

Bugs:
- Fixed a bug preventing async functions being used with horizontal line event.
- Fixed a bug causing the legend to show duplicate lines if the line was created after the legend.
- Fixed a bug causing the line hide icon to persist within the legend after deletion (#75)
- Fixed a bug causing the search box to be unfocused when the chart is loaded.

lightweight_charts/toolbox.py

@@ -0,0 +1,47 @@
+import json
+
+
+class ToolBox:
+    def __init__(self, chart):
+        from lightweight_charts.abstract import JS
+        self.run_script = chart.run_script
+        self.id = chart.id
+        self._save_under = None
+        self.drawings = {}
+        chart.win.handlers[f'save_drawings{self.id}'] = self._save_drawings
+        self.run_script(JS['toolbox'])
+        self.run_script(f'{self.id}.toolBox = new ToolBox({self.id})')
+
+    def save_drawings_under(self, widget: 'Widget'):
+        """
+        Drawings made on charts will be saved under the widget given. eg `chart.toolbox.save_drawings_under(chart.topbar['symbol'])`.
+        """
+        self._save_under = widget
+
+    def load_drawings(self, tag: str):
+        """
+        Loads and displays the drawings on the chart stored under the tag given.
+        """
+        if not self.drawings.get(tag):
+            return
+        self.run_script(f'if ("toolBox" in {self.id}) {self.id}.toolBox.loadDrawings({json.dumps(self.drawings[tag])})')
+
+    def import_drawings(self, file_path):
+        """
+        Imports a list of drawings stored at the given file path.
+        """
+        with open(file_path, 'r') as f:
+            json_data = json.load(f)
+            self.drawings = json_data
+
+    def export_drawings(self, file_path):
+        """
+        Exports the current list of drawings to the given file path.
+        """
+        with open(file_path, 'w+') as f:
+            json.dump(self.drawings, f, indent=4)
+
+    def _save_drawings(self, drawings):
+        if not self._save_under:
+            return
+        self.drawings[self._save_under.value] = json.loads(drawings)