NEW FEATURE: Trendlines, Rays and the Toolbox

- Added `trend_line` and `ray_line` to the Common Methods.

- Added the `toolbox` parameter to chart declaration. This allows horizontal lines, trend lines and rays to be drawn on the chart using hotkeys and buttons.
    - cmd-Z will delete the last drawing.
    - Drawings can be moved by clicking and dragging.

- Added the `render_drawings` parameter to `set`, which will keep and re-render the drawings displayed on the chart (useful for multiple timeframes!)

Horizontal Lines
- The `horizontal_line` method now returns a HorizontalLine object, containing the methods `update` and `delete`.
- Added the `interactive` parameter to `horizontal_line`, allowing for callbacks to be emitted to the `on_horizontal_line_move` callback method when the line is dragged to a new price (stop losses, limit orders, etc.).

Enhancements:
- added the `precision` method to the Common Methods, allowing for the number of decimal places shown on the price scale to be declared.
- Lines displayed on legends now have toggle switches, allowing for their visibility to be controlled directly within the chart window.
- when using `set`, the column names can now be capitalised, and the `date` column can be the index.

Changes:
- Merged the `title` method into the `price_line` method.

lightweight_charts/util.py

@@ -27,7 +27,7 @@ class IDGen(list):
         var = ''.join(choices(ascii_lowercase, k=8))
         if var not in self:
             self.append(var)
-            return var
+            return f'window.{var}'
         self.generate()