[Patch] Fix #1365: convert-ly shouldn't remove Dynamics performer group

[Valentin Villenave]

Greetings everybody, here's a patch that (hopefully) addresses the
low-priority issue 1365.

I'm not sure if we've ever used convert-ly to insert comments in .ly
files, but I do think we should in this specific case: the
piano-centered dynamics template has been used by a *lot* of people in
the past, and it's much more safe IMO if convert-ly puts a comment as
some kind of a placeholder.

Please have a look at the patch (since it's basically a one-line
patch, I think using Rietveld here would be overkill).

http://code.google.com/p/lilypond/issues/attachmentText?id=1365&aid=-4862281631302526021&name=0001-Convert-ly-fix-regexp-for-Dynamics-context.patch

-    str = re.sub (r'(\\context\s*\{{1}[^\}]+\\name\s+"*Dynamics"*[^\}]*\}{1})',
-                  '', str)
+    str = re.sub
(r'(\\context\s*\{{1}[^\}]+\\type\s+\"?Engraver_group\"?\s+\\name\s+"*Dynamics"*[^\}]*\}{1})',
+                  '% [Convert-ly] The Dynamics context is now
included by default.', str)

Cheers,
Valentin.