add lookup support for undefined terms, with add

A user can now lookup up any term on the page, rather than only tracked terms. This primarily is relevent for multi-word terms. Full support for updates subsequent to a dictionary search on undefined terms, whereby update info fields will perform an add operation behind the scenes first.

Other minor fixes:
* proper deletion of sup tags when untracking a multi-word term
* no longer rending the popup info if no info exists