Work in progress for chord symbol spacing.

This expands the containing segment to allow space for the chord symbol.
Further work required to allow a chord symbol to overlap segments that
do not have their own chord symbol.
Allow harmony to span multiple segments.

Also add a style setting for minimum chordname spacing.
Add stretch to notes under a long chord symbol.

Also, allow chord symbols to overlap if separated vertically.
Remove debug code and update some comments
Adds more actions and shortcuts:

*) new shortcuts for increase/decrease note pad value
*) HARMONY/FIGBASS: shortcuts for 'measured' advances
*) HARMONY/FIGBASS: shortcuts for jump to prev/next measure
*) HARMONY: shortcuts for jump to prev/next beat

*) Allow to combine shortcuts for TAB frets > 9 (for instance, use "fret-1" "fret-0" shortcuts to generate a fret '10')
Fix #20615:

In the New Score wizard and in the Instruments dlg box, the "Staff Type" combo is lost when staves or parts are moved up or down.
Limit fret digit combinations to be within instrument max fret number.

Fix crash when displaying fret marks above the supported range.
Merge pull request #287 from mgavioli/Fix_#20615_Instr_dlg_staff_type_combo_lost_on_moving_staves

Fix #20615: Instr. dlg box: Staff Type combo lost on moving staves
Merge pull request #285 from mgavioli/shortcuts_HARM_FIGBASS

Shortcuts for Harmony and FiguredBass
clean up icons
reorganize synthesizer; add zita1 reverb
update synthesizer implementation
fix regression tests
some regression fixes
move driverFactory() into separate file
fixes for synthesizer
reorder synthesizer; enable zita1 by default; more cleanups
some fixes for windows and audio playback
Use a tight bounding box for Harmony layout.

Also normalise chord names to lower case when matching typed input.
fix regression: switch patch for fluid in mixer