Add toolbar widget for edit size of handler in diagram editor.

Add a combo box in the tool bar of diagram editor
to quickly change the size of the graphics handler item.

The sarto commit :D

NOTE
only available for diagram editor, element editor will
come later.

sources/ui/diagrameditorhandlersizewidget.h

@@ -0,0 +1,49 @@
+/*
+	Copyright 2006-2021 The QElectroTech Team
+	This file is part of QElectroTech.
+
+	QElectroTech is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, either version 2 of the License, or
+	(at your option) any later version.
+
+	QElectroTech is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with QElectroTech.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#ifndef DIAGRAMEDITORHANDLERSIZEWIDGET_H
+#define DIAGRAMEDITORHANDLERSIZEWIDGET_H
+
+#include <QWidget>
+
+namespace Ui {
+	class DiagramEditorHandlerSizeWidget;
+}
+
+/**
+ * @brief The DiagramEditorHandlerSizeWidget class
+ * A little widget with a combo box to edit the size of
+ * the graphics handler item in a QetDiagramEditor.
+ * Just create a new instance of this widget, everything
+ * is done by the widget itself.
+ */
+class DiagramEditorHandlerSizeWidget : public QWidget
+{
+		Q_OBJECT
+
+	public:
+		explicit DiagramEditorHandlerSizeWidget(QWidget *parent = nullptr);
+		~DiagramEditorHandlerSizeWidget();
+
+	private slots:
+		void on_comboBox_currentIndexChanged(int index);
+
+	private:
+		Ui::DiagramEditorHandlerSizeWidget *ui;
+};
+
+#endif // DIAGRAMEDITORHANDLERSIZEWIDGET_H