Add "Export alignment" the "Export/Import" menu

Some export options are not obvious.
1. Open a multiple alignment file.
2. You want to export that alignment into another file with another multiple alignment format.
3. Open context menu of the document. Select "Export document". That is the option that you needed
4. Open context menu of the object. In the "Export/Import" menu there are no options to export alignment. This is not really convenient since users might not know about the "Export document" option.

The question on the forum: http://ugene.unipro.ru/forum/YaBB.pl?num=1363424169/0#1