XT8 build 4694 microSD voices (DX7 + pluck)

Copy the DX7 and PLUCK folders to the root of the Circuit Tracks
microSD card.
DX7/XT8 Starter.syx is a standard 32-voice DX7 bank (original XT8
voices, not Yamaha ROM data). Add your own DX7 .syx files to the same
folder: single voices (163 bytes) and 32-voice banks (4104 bytes),
any file name. The browser lists them in alphabetical order, a bank
as its 32 voices, up to 256 voices. No conversion step is needed.
PLUCK/00_PLUCK.PLK holds the 32 pluck v2 presets; 00_PLUCK.TXT lists
their names in pad order (row 1-2 of the browser's pluck tab).
The DSP program itself is in the firmware: nothing else is
needed on the card, and old DX7/*.X7B, Tracks/XTE*.P5? or XT8DSP.P56
files are ignored by this build.
