Clang: Use clang-format for indentation

This is the new experimental plugin based on LibFormat.

It replaces the default indenter for CppEditorDocument
and applies clang-format after the CR or the set of 'electric'
characters.

Uses the global .clang-format kept in QtC settings or
the one for current project. Both can be configured.

For indentation some style modifications and code manipulations
are done to prevent line shrinking when it's not expected.

Manual indentation uses unmodified style from .clang-format file.

Change-Id: I6279b805e418e1804b553efa615f5c843f395a58
Reviewed-by: Marco Bubke <marco.bubke@qt.io>

src/plugins/clangformat/clangformatconfigwidget.h

@@ -0,0 +1,57 @@
+/****************************************************************************
+**
+** Copyright (C) 2018 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of Qt Creator.
+**
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3 as published by the Free Software
+** Foundation with exceptions as appearing in the file LICENSE.GPL3-EXCEPT
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-3.0.html.
+**
+****************************************************************************/
+
+#pragma once
+
+#include <QWidget>
+
+#include <memory>
+
+namespace ProjectExplorer { class Project; }
+
+namespace ClangFormat {
+namespace Internal {
+
+namespace Ui {
+class ClangFormatConfigWidget;
+}
+
+class ClangFormatConfigWidget : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit ClangFormatConfigWidget(ProjectExplorer::Project *project = nullptr,
+                                     QWidget *parent = nullptr);
+    ~ClangFormatConfigWidget();
+    void apply();
+
+private:
+    ProjectExplorer::Project *m_project;
+    std::unique_ptr<Ui::ClangFormatConfigWidget> m_ui;
+};
+
+} // namespace Internal
+} // namespace ClangFormat