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/qetproject.cpp

@@ -112,6 +112,14 @@ QETProject::~QETProject() {
 	qDeleteAll(m_diagrams_list);
 }
 
+/**
+ * @brief QETProject::uuid
+ * @return the uuid of this project
+ */
+QUuid QETProject::uuid() const {
+	return m_uuid;
+}
+
 /**
  * @brief QETProject::init
  */