Performs a recursive copy from src to dest.
| src | 
                 the file/folder to recursively copy  | 
            
| dest | 
                 the target file/folder that will be created as a result of the copy  | 
            
| flags | 
                 the GLib.FileCopyFlags  | 
            
| cancellable | 
                 a GLib.Cancellable  | 
            
| GLib.Error | 
                 if an error occurs while copying the directory  |