[libcalamares] Move CommandList into libcalamares

- Move CommandList so it can be used from more modules than
   just ShellProcess
 - Allow a CommandList to run itself. This centralizes
   code for executing one or more commands and simplifies
   the ShellProcess module.

Various small cleanups:
 - mention instance id in log message
 - code formatting / style

src/libcalamares/utils/CommandList.h

@@ -0,0 +1,55 @@
+/* === This file is part of Calamares - <https://github.com/calamares> ===
+ *
+ *   Copyright 2018, Adriaan de Groot <groot@kde.org>
+ *
+ *   Calamares 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 3 of the License, or
+ *   (at your option) any later version.
+ *
+ *   Calamares 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 Calamares. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef COMMANDLIST_H
+#define COMMANDLIST_H
+
+#include "Job.h"
+
+#include <QStringList>
+#include <QVariant>
+
+namespace CalamaresUtils
+{
+
+class CommandList : protected QStringList
+{
+public:
+    CommandList( bool doChroot = true );
+    CommandList( const QVariant& v, bool doChroot = true );
+    ~CommandList();
+
+    bool doChroot() const
+    {
+        return m_doChroot;
+    }
+
+    Calamares::JobResult run( const QObject* parent );
+
+    using QStringList::isEmpty;
+    using QStringList::count;
+    using QStringList::cbegin;
+    using QStringList::cend;
+    using QStringList::const_iterator;
+
+private:
+    bool m_doChroot;
+} ;
+
+}  // namespace
+#endif // COMMANDLIST_H