allow toml for references

[miekg]

I might be nice to allow toml syntax for reference, so that we unify the preamble (which is in toml) with the references. Downside is that all references come in XML format, so you need to reformat that. We already support the XML from the references natively; so not sure how much functionally this adds.

[miekg]

should be relatively easy as we already have all the data structures in place. The only hard part is detecting the toml during parse time - as it just looks like text.

I.e. we have

<reference anchor='lottor' target='namedroppers@internic.net'>
 <front>
 <title>Domain Name Survey</title>
  <author initials='M.' surname='Lottor' fullname='M. Lottor'></author>
  <date year='1997' month='January'/>
 </front>
 </reference>

what would be a good TOML alternative that we can pick up? author can/should be taken from the toml title block.

May something ala:

[reference]
anchor = "bla"
target = "foo"
...

[miekg]

seems better easier to not do this and just use the reference and referencegroup.