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

.clang-format

@@ -44,7 +44,7 @@ BreakConstructorInitializersBeforeComma: false
 BreakConstructorInitializers: BeforeComma
 BreakAfterJavaFieldAnnotations: false
 BreakStringLiterals: false
-ColumnLimit: 120
+ColumnLimit: 100
 CompactNamespaces: true
 ConstructorInitializerAllOnOneLineOrOnePerLine: false
 ConstructorInitializerIndentWidth: 4