shinywidgets 0.3.0

• The @render_widget decorator now attaches a widget (and value) attribute to the function it decorates. This allows for easier access to the widget instance (or value), and eliminates the need for register_widget (which is now soft deprecated). (#119)
• Added decorators for notable packages that require coercion to the Widget class: @render_altair, @render_bokeh, @render_plotly, and @render_pydeck. Using these decorators (over @render_widget) helps with typing on the widget attribute. (#119)
• The .properties() method on altair.Chart object now works as expected again. (#129)
• Reduce default plot margins on plotly graphs.