C++: remove builtin FollowSymbol dependency from CppEditor

Move FollowSymbolUnderCursor to CppTools and
builtin member ownership to internal model manager.

Change-Id: I97a4f744ec1709ccc0b34fb67b58680973ef566f
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

src/plugins/cpptools/cppeditorwidgetinterface.h

@@ -0,0 +1,46 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 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 "cpptools_global.h"
+
+#include <texteditor/codeassist/assistenums.h>
+
+namespace TextEditor { class IAssistProvider; }
+
+namespace CppTools {
+
+class CPPTOOLS_EXPORT CppEditorWidgetInterface
+{
+public:
+    virtual void showPreProcessorWidget() = 0;
+    virtual void updateSemanticInfo() = 0;
+
+    virtual void invokeTextEditorWidgetAssist(TextEditor::AssistKind assistKind,
+                                              TextEditor::IAssistProvider *provider) = 0;
+};
+
+} // namespace CppTools