add newline feature to the text node, add about window with credits, add about menu with submenus

src/app_dialogs.cpp

@@ -3,6 +3,7 @@
 #include "node_dialog_open.h"
 #include "node_dialog_browse.h"
 #include "node_dialog_cloud.h"
+#include "node_about.h"
 
 std::shared_ptr<NodeProgressBar> App::show_progress(const std::string& title)
 {
@@ -17,6 +18,17 @@ std::shared_ptr<NodeProgressBar> App::show_progress(const std::string& title)
     return pb;
 }
 
+void App::dialog_about()
+{
+    auto dialog = std::make_shared<NodeAbout>();
+    dialog->m_manager = &layout;
+    dialog->init();
+    dialog->create();
+    dialog->loaded();
+
+    layout[main_id]->add_child(dialog);
+    layout[main_id]->update();
+}
 void App::dialog_newdoc()
 {
     auto show_dialog = [this] {