Adds the opened file to the App's recent files list: seen in Blender dock
icon's context menu, or App Exposé.
Also add clear recent files operator in File menu -> Open Recent.
File is added to recent files in WM_OT_open_mainfile also, in
addition to WM_OT_save_mainfile.
Contributed by @Yevgeny Makarov (jenkm) also.

Less intrusive alternative is adding it to Blender app menu. It is macOS only,
does not affect Splash Screen, doesn't affect "Open Recent" submenu.

Clearing recent files programmatically:

[[NSDocumentController sharedDocumentController] clearRecentDocuments:nil];

To add the standard "Open Recent" menu:

NSMenu *recentMenu = [[NSMenu alloc] initWithTitle:@"Open Recent"];
[recentMenu performSelector:@selector(_setMenuName:) withObject:@"NSRecentDocumentsMenu"];