supress input cells in latex output
todo
change format: [#ref] -> #ref'
only convert links after consuming
wip: equation references
implement equation references
todo: allow #id to be anywhere in attrs
implement a Figure type
add InternalRef type
use figure styles dict
wip: reduce code

todo: make two passes with current consume_references. First pass just
logs the references in the refdict, second pass actually replaces them.
links to information
wip: new spec for multiple refs

todo: define html and latex output