Define absolute-dynamics as a customizable event-function (issue 20660044)

[dak]

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly
File ly/dynamic-scripts-init.ly (right):

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode7
ly/dynamic-scripts-init.ly:7: #(define safe-dynamics ; see midi.scm
What's "safe" about them?

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode37
ly/dynamic-scripts-init.ly:37: (map (lambda (str)
for-each if you don't want to return a value.

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode39
ly/dynamic-scripts-init.ly:39: (ly:format "\"~a\" = \\dynamic \"~a\""
str str)))
Ugh.  I mean, really really ugh.

Why not use ly:parser-define! here?

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode66
ly/dynamic-scripts-init.ly:66: ; we can.
You could just dig through the markup and see whether you find a
\dynamic-string inside.  That's not likely helpful for instructions like
"definitely not ff", but seems better than nothing.

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode79
ly/dynamic-scripts-init.ly:79: (display "tataaaa :"))
I don't think that kind of output is usual for LilyPond.

https://codereview.appspot.com/20660044/diff/1/ly/dynamic-scripts-init.ly#newcode89
ly/dynamic-scripts-init.ly:89: (_ "Dynamic \"~a\" does not have an
acceptable volume: ~a") arg vol)))
Excessive output, isn't it?

https://codereview.appspot.com/20660044/diff/1/scm/define-markup-commands.scm
File scm/define-markup-commands.scm (right):

https://codereview.appspot.com/20660044/diff/1/scm/define-markup-commands.scm#newcode2716
scm/define-markup-commands.scm:2716: The dynamic font is only used in
words that contain no other
This is just too ugly and unreliable as an interface.

https://codereview.appspot.com/20660044/