Fix exported headers in Core and TextEditor.

- Unexport Core::Internal::MainWindow and remove its includes.
- Move RssFetcher from Core::Internal to Core.
- Unexport CopyTaskHandler.
- Move TextEditor's completion support and Refactor Overlay
  helper classes from TextEditor::Internal to TextEditor as they
  are exported.
- Move internal BaseTextBlockSelection into private header.
- Unexport TextEditorOverlay as they are not used.

src/plugins/texteditor/refactoroverlay.cpp

@@ -1,10 +1,42 @@
-#include "refactoroverlay.h"
-#include <QPainter>
-#include <QTextBlock>
-#include "basetextdocumentlayout.h"
-#include <QDebug>
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2010 Nokia Corporation and/or its subsidiary(-ies).
+**
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** Commercial Usage
+**
+** Licensees holding valid Qt Commercial licenses may use this file in
+** accordance with the Qt Commercial License Agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and Nokia.
+**
+** GNU Lesser General Public License Usage
+**
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at http://qt.nokia.com/contact.
+**
+**************************************************************************/
 
-using namespace TextEditor::Internal;
+#include "refactoroverlay.h"
+#include "basetextdocumentlayout.h"
+#include "basetexteditor.h"
+
+#include <QtGui/QPainter>
+#include <QtGui/QTextBlock>
+
+#include <QtCore/QDebug>
+
+namespace TextEditor {
 
 RefactorOverlay::RefactorOverlay(TextEditor::BaseTextEditor *editor) :
     QObject(editor),
@@ -62,4 +94,4 @@ void RefactorOverlay::paintMarker(const RefactorMarker& marker, QPainter *painte
     m_maxWidth = qMax((qreal)m_maxWidth, x + sz.width() - offset.x());
 }
 
-
+} // namespace TextEditor