added highlight to element on hover by decreasing the opacity of the bac...

...kground elements using a global higlight function

@jebeck can you look at it, i think its ready but i'd like to hear what you think of the code and the resulting interaction.
@ianjorgensen We're already getting the `bgInput` with the `payload` on MedT `wizard` events, we're just visualizing from them. If your point here is incorporating the `bgInput` into the tooltip info, we're dependent on https://trello.com/c/JRezSOoo for dynamically sizeable tooltips to make that happen.