Make transposed tunes use the original audio. 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.

X:1
T:Orange in Bloom
M:6/8
S:Bacon (CJS MSS)
A:Sherborne
O:English
R:Jig
P:A.(AB3)4(AC3)4A
K:G
I:speed 450
P:A
|:     EGE       DGA   | BdB   A2B   | GEE   DGA   | BGG   G3   :|\
P:B
       BAB/2c/2  d2B   | AGA   Bcd   |
       edB   AGA   | BAG   E2D  |\
       EGE       DGA   | BdB   A2B   | GEE   DGA   | B2G   G3   ||
M:4/4
P:C
I:speed 150
       BABc      d2 B2 | AG A2 Bc d2 | ed B2 AG A2 | BA G2 E3 D |
M:6/8
I:speed 450
       EGE       DGA   | BdB   A2B   | GEE   DGA   | BGG   G3   ||