Designer: Prepare re-implementation of "Goto Slot".

...making use of the new code model features. Move code to
separate file. Make it possible to obtain path to generated
header file from project manager.

src/plugins/designer/codemodelhelpers.h

@@ -0,0 +1,54 @@
+/**************************************************************************
+**
+** This file is part of Qt Creator
+**
+** Copyright (c) 2009 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.
+**
+**************************************************************************/
+
+#ifndef CODEMODELHELPERS_H
+#define CODEMODELHELPERS_H
+
+#include <QtCore/QtGlobal>
+
+QT_BEGIN_NAMESPACE
+class QString;
+class QStringList;
+QT_END_NAMESPACE
+
+namespace Designer {
+namespace Internal {
+
+// Goto slot invoked by the designer context menu. Either navigates
+// to an existing slot function or create a new one.
+bool navigateToSlot(const QString &uiFileName,
+                    const QString &objectName,
+                    const QString &signalSignature,
+                    const QStringList &parameterNames,
+                    QString *errorMessage);
+
+} // namespace Internal
+} // namespace Designer
+
+#endif // CODEMODELHELPERS_H