fixes on demos/wtc1fuga5.mscz

Hi,

I found some errors/typos in the wtc1fuga5 demo-sheet and now have managed to fix it.
Changes include:

- missing note inserted in Bar 13, 2nd voice, 4th beat (c'#)
- some misplaced notes and typos
- layout corrections, as moving fingers and rests, broken metronome text