move MessageItemDelegate to its own file

item_delegates/MessageItemDelegate.cpp

@@ -0,0 +1,26 @@
+//
+// Moved from Configuration.cpp
+//
+
+#include "MessageItemDelegate.hpp"
+
+#include <QLineEdit>
+#include <QRegExpValidator>
+
+//
+// Class MessageItemDelegate
+//
+//	Item delegate for message entry such as free text message macros.
+//
+MessageItemDelegate::MessageItemDelegate(QObject *parent): QStyledItemDelegate{parent}
+{
+}
+
+QWidget *MessageItemDelegate::createEditor(QWidget *parent, QStyleOptionViewItem const &, QModelIndex const &) const
+{
+  QRegularExpression message_alphabet{"[- @A-Za-z0-9+./?#<>;$]*"};
+  auto editor = new QLineEdit{parent};
+  editor->setFrame(false);
+  editor->setValidator(new QRegularExpressionValidator{message_alphabet, editor});
+  return editor;
+}