Improve Plotly Support

[rjzupkoii]

Support for Plotly was added with #3137, but more functionality can be added. Specifically:

• Plots fail to respond to changes in the theme and a callback should be added to enable redrawing.
• The code is intended to be updated for better theming since the theme is imported from assets/js/theme.js but currently the feature is not in place.
• Better documentation on how to use Plotly via HTML and JavaScript should be added to the Wiki.