- Use buttons so that facets can be expanded or collapsed using the keyboard.
- Make it possible to select a hierarchical facet value also when a screen reader is active (they tend to swallow normal keyboard events).
- Use role="heading" for the srmessage so that it can be easily found and read.
- Use additional sr text in active filter list and for selected checkbox facets to signify that the link will remove the filter.

A mixture of .data( and .attr('data- updated and read from different locations.

- Use jQuery to handle data attributes (needed for IE 9/10).
- Fix issue with all IE versions where Recaptcha dialogs don't accept any button presses.

Good catch Travis! :)

Conflicts:
	themes/bootstrap3/js/lightbox.js

- Adds new configuration setting to pop up lightbox to explore facet lists more deeply; currently supported by both Summon and Solr.

- Replace getters with public properties for simplicity/perforamnce.