Let calc-{fingering,string-number,stroke-finger}::calc-text look at event 'text

Let calc-{fingering,string-number,stroke-finger}::calc-text look at event 'text

This slightly increases the number of property lookups, and the same
function can be achieved using a tweak.  However, it seems more
natural to attach any overriding text (in the case of non-standard
elements like thumbs or other) directly to the event in question.