Terminal strip Xref is clickable

When user hover the Xref string of a terminal, the string color change
to blue to advise user the xref is clickable. Double click on the blue
Xref go the folio of the terminal and zoom the view to the terminal.

sources/TerminalStrip/physicalterminal.h

@@ -86,6 +86,7 @@ class PhysicalTerminal
 		int levelCount() const;
 		int levelOf(const QSharedPointer<RealTerminal> &terminal) const;
 		QVector<QSharedPointer<RealTerminal>> realTerminals() const;
+		QSharedPointer<RealTerminal> realTerminal(int pos) const;
 		QUuid uuid() const;
 		int pos() const;
 		int realTerminalCount() const;