- Removed Column::inputFilter(), since messing with it from the outside wreaks
havoc with ColumnStringIO. Fixes input problems after auto-filling cells.
- Changed lastSelected(Column|Row) in TableView and MatrixView to return -2 in
case of no selection instead of -1. Rationale: iteration from firstSelected*
to lastSelected* automatically becomes empty in this case. Fixes what would
otherwise be a bug in Table::recalculate(), but also makes sure this won't
crop up elsewhere in the future.