Fix Strokes Spanning Multipe voices

frethandfinger.js :: change font size to 9, bold for better readability.

strokes.js :: add all_voices option (true or false)  to constructor.
Default is true. Revise draw function to span all multi voice notes if
all_voices is true.

stringnumber_tests :: remove  references to deprecated
Strokes.addEndNote function

strokes_tests.js :: remove  references to deprecated Strokes.addEndNote
function. Add new test for multi-voice notation and tablature