Reapply "Add cable management: drawing, cores, numbering, cross-references and cable list"

This reverts commit 2bb3343d2d.

sources/undocommand/linkelementcommand.cpp

@@ -17,6 +17,7 @@
 */
 #include "linkelementcommand.h"
 
+#include "../cable/cablemanager.h"
 #include "../conductorautonumerotation.h"
 #include "../diagram.h"
 #include "../diagramposition.h"
@@ -59,6 +60,23 @@ static QString plcCrossRefText(Element *master, Element *slave)
 		xrp.slaveLabel(), seq, master->diagram(), master);
 }
 
+/**
+	@brief refreshCableLabelsForReport
+	A folio report carries a cable core over to the next sheet, so
+	making or breaking such a link changes which wires belong to which
+	cable. Work the cable fields out again straight away, so the wire
+	coming out of the linked arrow shows the cable right after the link
+	is made -- and drops it right after the link is taken away.
+	@param element the element the link was made or broken on
+*/
+static void refreshCableLabelsForReport(Element *element)
+{
+	if (!element || !(element->linkType() & Element::AllReport)) return;
+	if (Diagram *diagram = element->diagram()) {
+		CableManager::refreshLabels(diagram->project());
+	}
+}
+
 /**
 	@brief LinkElementCommand::LinkElementCommand
 	Constructor
@@ -302,6 +320,7 @@ void LinkElementCommand::undo()
 	}
 
 	makeLink(m_linked_before);
+	refreshCableLabelsForReport(m_element);
 	QUndoCommand::undo();
 }
 
@@ -329,6 +348,7 @@ void LinkElementCommand::redo()
 		}
 		m_first_redo = false;
 	}
+	refreshCableLabelsForReport(m_element);
 	QUndoCommand::redo();
 }