Accessibility review

The following accessibility issues should be fixed.

- The content begins here header should be an `h1`
- The top navigation search label is orphaned
- The `l` accesskey element doesn't exist on all pages
- The checkboxes in manageaccess need a label
- The autosuggest component needs for the next item field
- The comment field in the comments widget needs a label
- The various upload fields need a label
- The add links field needs a label
- Revision images need alternative text

These issues were found using the Wave Firefox toolbar.