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.

docs/source/_ext/styles.py

@@ -0,0 +1,16 @@
+import pygments.styles
+
+
+bulb = pygments.styles.get_style_by_name('lightbulb')
+sas = pygments.styles.get_style_by_name('sas')
+
+
+class DarkStyle(bulb):
+    background_color = '#1e2124ff'
+
+
+class LightStyle(sas):
+    background_color = '#efeff4ff'
+
+
+