Shortcuts for Harmony and FiguredBass

Adds more actions and shortcuts:

*) HARMONY/FIGBASS: actions for 'measured' advances (same default shortcuts as old hard-coded [Ctrl]+[#] keystrokes)
*) HARMONY/FIGBASS: actions for jump to prev/next measure (same default shortcuts as old hard-coded [Tab]/[Shift][Tab] keystrokes)
*) HARMONY: actions for jump to prev/next beat (same default shortcuts as old hard-coded [;]/[:] keystrokes)
*) new actions for increase/decrease note pad value (preparatory for TAB input mode improvements; no default shortcuts defined yet)

Also:
*) Allow to combine shortcuts for TAB frets > 9 (for instance, "fret-1" and  "fret-0" shortcuts can be used in sequence to generate a fret '10')
*) re-ordered actions and shortcuts roughly by topic; cleaned up old commented out code