* Only change aria-pressed if it's not an input-based radio or checkbox group

aria-pressed="true"/aria-pressed="false" is really only useful for
making on/off toggles out of, say, `<button>` elements. the attribute is
useless (and potentially confusing/conflicting) on, say, `<label>`
elements for an existing `<input type="radio">` or similar.

* Add unit test for buttons.js and radio/checkbox inputs in button groups

This allows for keyboard navigation (e.g. arrow keys left/right to
trigger different radio buttons) following an initial mouse click
interaction

Bootstrap’s .button styles can be applied to other elements, such as labels, to provide checkbox or radio style button toggling.

When the checkbox or radio state is changed, there should be triggered the change event. Currently, the change event is triggered on the Button, which is not correct. Only input fields do support the change event.

Errata from:
* 8ce5da30
* 5d3144e8
which missed a few numbers.

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add modal my gawd