Placing an auto-numbered element or conductor advances a shared
NumerotationContext counter (QETProject::addConductorAutoNum/
addElementAutoNum) as a side effect that sat entirely outside the undo
stack. Undoing the placement removed the visible number but left the
counter advanced, so every undo of an auto-numbered placement silently
burned a number, with no way to get it back short of a manual reset.
Adds SetAutoNumContextCommand, a small QUndoCommand storing the old/new
NumerotationContext and calling the matching add*AutoNum() setter on
undo()/redo() -- the same shape QPropertyUndoCommand already uses next
to it in ConductorAutoNumerotation::applyText().
Wires it into the two conductor call sites (the static newProperties(),
and numerateNewConductor(), both in ConductorAutoNumerotation) and the
element call site (Element::setUpFormula(), called from
DiagramEventAddElement::addElement() when a new element is dropped onto
a diagram). setUpFormula() now takes an optional parent QUndoCommand;
addElement() calls it before pushing its own undo_object so the counter
change lands in the same undo macro as the element's placement -- one
Ctrl+Z reverts both together, instead of leaving the counter adrift.
The project-properties config dialog's own add*AutoNum() calls (editing
the numbering rule itself, not a side effect of placing something) are
deliberately left untouched, as are the load-time folio-sequential
bookkeeping calls in Diagram::loadElmtFolioSeq()/loadCndFolioSeq() and
the bulk folio-renumbering passes in QETProject -- none of those run as
part of an undoable user gesture.
Implements the scope proposed in discussion #608.
ispyisail