Merge from vendor branch TNF:

Merge from vendor branch TNF:
Import tex-fixme.

This package provides you with a way of inserting fixme notes in your
documents.  Such notes can appear inline, as marginal notes,
footnotes, index entries, in the log file and as warnings on stdout.
It is also possible to summarize them in a list.  When you switch from
draft to final mode, any remaining fixme note will be logged, but
removed from the document's body.  Additionally, critical notes will
abort compilation with an informative message.  FiXme also comes with
support for AUC-TeX.