Add documents

Add documents, document views and a document store to manage document and which one is displayed.

• The MainWindow make calls to the VivyDocumentStore to create the documents and the views
• The VivyDocumentStore create the documents
• The VivyDocumentView is only here to have a view, it won't hold any data
• The VivyDocument can be manipulated in any part of the code
• Widgets view the VivyDocument through the VivyDocumentView
• Add the VivyApplication that will hold the window and the non-graphic data
• The main window can get the currently selected main document

src/Ass/Ass.h

+#ifndef VIVY_ASS_ASS_H
+#define VIVY_ASS_ASS_H
+
+#include "Char.h"
+#include "Line.h"
+#include "Syl.h"
+#include "Style.h"
+
+#endif // VIVY_ASS_ASS_H