extract meta data from lilypond compilation

* write that as yaml file next to the other outputs
* extract lyrics
* makes chordpro export work in songbooks
* more metadata for chordpro export

private_includes/book/toc_include.ily

@@ -370,6 +370,9 @@ headerToTOC = #(define-music-function (parser location header label) (ly:book? s
 #(define csv-write sxml->csv)
 
 #(define-markup-command (write-toc-csv layout props) ()
+  ;; Dateiname wie bei \write-book-yaml/\write-book-chordpro: der
+  ;; Ausgabename des Buchs mit angehaengtem .csv statt fest "toc.csv".
+  (define csv-filename (string-append (ly:parser-output-name) ".csv"))
   (define (csv-escape field)
     (if (string-null? field)
         field
@@ -453,7 +456,7 @@ headerToTOC = #(define-music-function (parser location header label) (ly:book? s
                   (format-info-paragraphs (headervar-or-empty 'pronunciation))
               ))))
             (alist-delete 'markupPage (alist-delete 'imagePage (alist-delete 'emptyPage song-list))))))
-    (call-with-output-file "toc.csv"
+    (call-with-output-file csv-filename
       (lambda (port)
        (csv-write (cons '(
         "filename"