2012-11-26 ago more general sendback properties;
2012-11-26 ago tuned signature;
2012-11-25 ago Isabelle-specific implementation of quasi-abstract markup elements -- back to module arrangement before d83797ef0d2d;
2012-11-22 ago defer interpretation of markup via implicit print mode;
2012-11-22 ago some support for implicit senback, meaning that it uses the caret position instead of explicit command exec_id;
2012-11-22 ago more abstract Sendback operations, with explicit id/exec_id properties;