Use a style format for duration field for xlm file exporting
Use a style format for duration field for xlm file exporting

lino-framework/lino,lsaffre/lino,lino-framework/lino,lsaffre/lino,lsaffre/lino,lino-framework/lino,lsaffre/lino,lino-framework/lino,lino-framework/lino,lsaffre/lino