Added
* Improved widget handling, now use a dict to store components instead of parsing code.
Makes it possible to subscribe to events with expressions for the component.
* Cache behaves like dict, e.g. `cache['data'] = [1, 2, 3]`.
* Support Ant theme to customize all Ant components, added in the `App` class.
* Vertical option for slider. (204)
* Document run command.
* Document exceptions.
Breaking
* Removed cache `save` and `load` functions in favor of dict functionality.