Sets lilypond-id message to type progress (issue 5848056)

[PhilEHolmes]

Reviewers: Graham Percival, Julien Rioux, dak, Reinhold,

Message:
Please review

Description:
We're now down to about 460 lines of output from make doc -s, and
"lilypond-book.py (GNU LilyPond) 2.15.34" is nearly 20% of them.  If the
way this is output is changed to progress(), then running -book with -l
WARN (which we do) does not output these to terminal.

Please review whether this is the best approach.

Please review this at http://codereview.appspot.com/5848056/

Affected files:
  M scripts/lilypond-book.py


Index: scripts/lilypond-book.py
diff --git a/scripts/lilypond-book.py b/scripts/lilypond-book.py
index  
8847419fe0dc46e698e06873f7494e4bf0bae6f2..623ef16fc618b5579462e8dbddd4523692cd3e9a  
100644
--- a/scripts/lilypond-book.py
+++ b/scripts/lilypond-book.py
@@ -96,13 +96,12 @@ def exit (i):
     else:
         sys.exit (i)

-def identify ():
-    ly.encoded_write (sys.stdout, '%s (GNU LilyPond) %s\n' %  
(ly.program_name, ly.program_version))
-
 progress = ly.progress
 warning = ly.warning
 error = ly.error

+def identify ():
+    progress(_ ('%s (GNU LilyPond) %s' % (ly.program_name,  
ly.program_version)))

 def warranty ():
     identify ()