#41 order of files in audio palette

[Helen Varley Jamieson]

currently, the audio files don't appear to be in any order when they are listed in the audio palette on a stage; this is problematic when you have quite a few files & have to scroll up & down to find the one you want. ideally they should be ordered alphabetically, as the avs & backdrops are - this would allow you to number them to control the order.