The breadcrumbs accept attributes on each individual 'crumb', but this isn't documented.

The select accepts attributes on each individual <option>, but this isn't documented.

describedBy is listed as an option for both the character count and the textarea component, but in both cases this is actually a variable used only within the component, that cannot be passed in as part of `params`.

- Use 'params' instead of 'arguments'.
- Add missing html and text options for the 'meta' section of the footer.

Currently we reuse the `item` variable within a nested for loop (`{% for item in params.navigation %}` is the outer loop, `{% for item in item.items %}` is the inner loop), which makes it difficult to understand what is going on (I'm surprised this works!)

This updates the outer loop to use `{% for nav in params.navigation %}` instead.

Radios do not accept a `name` for each radio button, as unlike checkboxes radios within the same fieldset should always have the same name.

- Add undocumented 'title' option
- Add undocumented `attributes` option for each panel
- Reformat panel options to be represented as a nested object