Change \bendAfter and \rightHandFinger into event functions (issue 6102045)

[graham]

LGTM


http://codereview.appspot.com/6102045/diff/1/Documentation/notation/fretted-strings.itely
File Documentation/notation/fretted-strings.itely (right):

http://codereview.appspot.com/6102045/diff/1/Documentation/notation/fretted-strings.itely#newcode1589
Documentation/notation/fretted-strings.itely:1589: <e\rightHandFinger 2>
oh god.  At one point, we tried to eliminate all #-less numbers to avoid
confusion like this.

I know that you're proud of parser work which lets us write a bare 2
here, but I fear this would lead to user confusion and not be a net
positive.  Could we leave the #2 > there?

http://codereview.appspot.com/6102045/