musescore: remove non-free score

Based on the original helper at
http://listas.trisquel.info/pipermail/trisquel-devel/2014-June/000852.html

helpers/make-musescore

+#!/bin/sh
+#
+#    Copyright (C) 2014 Kouta Ikematsu  <kame55-itasenpara123 at y2.dion.ne.jp>
+#    Copyright (C) 2015 Santi Rodriguez <santi at trisquel.info>
+#
+#    This program is free software; you can redistribute it and/or modify
+#    it under the terms of the GNU General Public License as published by
+#    the Free Software Foundation; either version 2 of the License, or
+#    (at your option) any later version.
+#
+#    This program is distributed in the hope that it will be useful,
+#    but WITHOUT ANY WARRANTY; without even the implied warranty of
+#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+#    GNU General Public License for more details.
+#
+#    You should have received a copy of the GNU General Public License along
+#    with this program; if not, write to the Free Software Foundation, Inc.,
+#    51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+#
+# Changelog:
+#
+# 2014/06/24: Fixing "sed" command.
+#
+#
+
+VERSION=1
+
+. ./config
+
+
+## Remove non-free score
+rm ./mscore/demos/prelude.mscx
+sed -i /prelude.mscx/d ./mscore/demos/CMakeLists.txt
+echo "#changelog: `env LANG=C date '+%Y-%m%d'` Trisquel-package-helper: Remove prelude.mscx" >> ./mscore/demos/CMakeLists.txt
+
+## Write changelog and compile.
+changelog "Removed non-free score"
+compile
+