Emit events on component interaction

[rreusser]

Components currently trigger API calls, which in turn trigger events. Power users may wish to hook directly into component interactions without the intermediate step of an API call. Should this be plotly_updatemenuschange and similar?

[rreusser]

You can see a workaround with a dummy restyle here: http://codepen.io/rsreusser/pen/yawxgp?editors=0010

[rreusser]

Solved in #1126 and #1128