Improve predefined-fretboards

Improve predefined-fretboards

Add fret-diagram-verbose input option for predefined fretboards

Add stringTunings as part of chord-shape key to allow the use
of two different instruments (e.g. ukelele and guitar)
simultaneously.

Add new variable type check predicate string-or-pair?

Change base-chord-shapes alist to chord-shape-table hashq

Update predefined-guitar* to match new syntax.

Add capo indication to verbose diagram definition