phpdoc tweaks
phpdoc improvements
more phpdoc improvements
Make admin_edit_field_html method not static.
Add new field type property to indicate whether field supports multiple default options

Only MSB and CB in core do this. It controls how the options are
rendered in the admin (with either radio buttons or checkboxes).
Remove dupe field property in MSB
Update admin_edit_field_html() to work with the recent changes
Use the supports_multiple_defaults property in another spot