Presets: implements presets

*) for percussion staves
*) as a setting in instruments.xml
Make preset names translatable.
initial: improve performance adding and removing KeySig
ChangeElement updates keymap for keySig change
Removed redundant <stafflines> tags from instruments.xml
Removed comments
Merge pull request #278 from mgavioli/Presets

Presets: for percussion staves and as instruments.xml setting
Merge pull request #280 from heuchi/keySig_improvements

Fix #20573 and improve performance of KeySig handling
fix layout of grace note hook
honor beam mode NO for grace notes
move ledgerline and stemslash into separate files
fix stemslash layout
cleanups