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')
Limit fret digit combinations to be within instrument max fret number.

Fix crash when displaying fret marks above the supported range.
Merge pull request #285 from mgavioli/shortcuts_HARM_FIGBASS

Shortcuts for Harmony and FiguredBass