more general notion of command span: command keyword not necessarily at start;
support for special 'private' prefix for local_theory commands;
clarified parse_spans, with related operations for document Thy_Output and editor Token_Markup;
Identifiers of some old CVS file versions
=========================================
src/Pure/General/file.ML 1.18 6cdd6a8da9b9
src/Pure/thm.ML 1.189 4b339d3907a0 (referenced in 25f28f9c28a3 as "2005-01-24 (revision 1.44)")
src/Pure/type.ML 1.65 0d984ee030a1