add share button and implement AirDrop share in OSX, update info.plist to set on Mac OS the default app for PPI, on iOS include the Documents/Inbox subfolder used to store the received files from AirDrop

src/app_dialogs.cpp

@@ -253,7 +253,11 @@ void App::dialog_browse()
         // load thumbnail test
         auto dialog = std::make_shared<NodeDialogBrowse>();
         dialog->m_manager = &layout;
-        dialog->search_path = work_path;
+#ifdef __IOS__
+        dialog->search_paths = {work_path, data_path + "/Inbox"};
+#else
+        dialog->search_paths = {work_path};
+#endif
         dialog->init();
         dialog->create();
         dialog->loaded();