Visitor addons:
 * footnotes
 * citations
 * docinfo
 * subtitle

Missing visit_ methods:
 * visit_generated
 * visit_revision
 * visit_address
 * visit_abbreviation
 * visit_copyright
 * visit_compound
 * visit_container
 * visit_subscript
 * visit_date
 * visit_rubric
 * visit_math
 * visit_attribution
 * visit_superscript
 * visit_docinfo_item
 * visit_organization
 * visit_contact
 * visit_acronyma

Attributes / Tags:
 * image align

Not working:
 * contents backlinks
 * contents class
 * list enumtype
