Add an <audio> tag to the bottom centre of the tune web page. Give it options for MP3 and
OGG files. Most browsers will play MP3, and the ones that won't (Firefox) will play OGG.
Since we now have to generate OGGs, add a download link as well.
The aim of MIDI and MP3 is to allow the user to hear what a tune sounds
like. For transposed bookes, I think this should be reused from the main
booke page, because hearing it at the transposed pitch isn't a major help.
And in fact given the way cello transposition is done, the sound won't
be transposed anyway. And Jane hasn't complained.
This will speed up building the bookes by removing audio generation,
the slowest process, from the transposed bookes.
Jim Hague