Lightweight-charts

- Fixed an issue which caused JavaScript variables of the same name to be declared twice.
- Refactored to allow the widget classes to use the subscribe_click method.

- Added support for PyQt.
- Refactored widgets to catch ModuleNotFoundErrors.

Fixes:
- Added missing docstrings (line.set(), chart.hide(), chart.exit()).
- Updated chart.exit() to destroy objects and terminate the webview process.
- Fixed WxChart not expanding correctly and removed its width and height parameters.
- Fixed KeyboardInterrupt error message when using show(block=True).

First release