[AppStream] Font metadata improvements

[Richard Hughes]

Hi Nathan, sorry for the delay.

On 29 April 2018 at 11:38, Nathan Willis <nwillis at glyphography.com> wrote:
> - <reserved_font_name>

Could these be <custom> tags? I don't think we have many
component-type-specific tags in the format so far.

> specimen

Could that be a <url type="specimen"> perhaps?

> designer_name

Is that much different to the <developer_name> tag?

Richard.