2010-08-20 wenzelm 2010-08-20 further clarification/unification of Position.Range and Text.Range concerning singularities: start offset is always included;
2010-08-19 wenzelm 2010-08-19 parameterized type Markup_Tree.Node; allow arbitrary interpretations, not just filtering; renamed Text.Range.intersect to Text.Range.restrict -- emphasize that it is not directly related to contains/overlaps;
2010-08-19 wenzelm 2010-08-19 added toString methods;
2010-08-19 wenzelm 2010-08-19 misc tuning and simplification;
2010-08-19 wenzelm 2010-08-19 Text.Range: improved handling of singularities;
2010-08-18 wenzelm 2010-08-18 refined notion of Text.Range;
2010-08-15 wenzelm 2010-08-15 some derived operations on Text.Range;
2010-08-15 wenzelm 2010-08-15 specific types Text.Offset and Text.Range; minor tuning;
2010-08-15 wenzelm 2010-08-15 moved Text_Edit to Text.Edit; tuned;