Add nomenclature model

Add class NomenclatureModel witch is used with QetGraphicsTableItem.
Add ProjectDataBase  class, the goal of this class is to store all
information of a project at an instant T to easilly find it. This class
is still in development and not provide all information that she should.

sources/dataBase/projectdatabase.h

@@ -0,0 +1,59 @@
+/*
+		Copyright 2006-2020 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 PROJECTDATABASE_H
+#define PROJECTDATABASE_H
+
+#include <QObject>
+#include <QSqlDatabase>
+#include <QSqlQuery>
+#include <QPointer>
+
+#include "qetproject.h"
+
+class Element;
+
+/**
+ * @brief The projectDataBase class
+ * This class wrap a sqlite data base where you can find several thing about
+ * the content of a project.
+ *
+ * NOTE this class is still in developement.
+ */
+class projectDataBase : public QObject
+{
+	Q_OBJECT
+
+	public:
+		projectDataBase(QETProject *project, QObject *parent = nullptr);
+		virtual ~projectDataBase() override;
+
+		QVector<QStringList> elementsInfoFromQuery(const QString &query);
+
+	private:
+		bool createDataBase();
+		void populateElementsTable();
+		static QHash<QString, QString> elementInfoToString(Element *elmt);
+		QStringList elementsInfoKeys() const;
+
+	private:
+		QPointer<QETProject> m_project;
+		QSqlDatabase m_data_base;
+		QSqlQuery m_insert_elements_query;
+};
+
+#endif // PROJECTDATABASE_H