Highlight and zoom to the filter boundary

I had trouble pulling secondary-color out of the instance config
dictionary in the settings.js template beacause it has a hypen in the
name. To solve the issue I created a pair of template tags to call the
``get`` method that could not be directly accessed in a {{ }} tag.
Merge pull request #464 from jwalgran/topic/select-boundary

Highlight and zoom to the filter boundary