Add menu item to clear the recent projects/files menus.

Task-number: QTCREATORBUG-5136

Change-Id: I27d5c86832277be9525d95fd1e38a3b86f620974
Reviewed-on: http://codereview.qt.nokia.com/496
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Daniel Teske <daniel.teske@nokia.com>

src/plugins/coreplugin/filemanager.cpp

@@ -1077,6 +1077,17 @@ void FileManager::addToRecentFiles(const QString &fileName, const QString &edito
     d->m_recentFiles.prepend(RecentFile(fileName, editorId));
 }
 
+/*!
+    \fn void FileManager::clearRecentFiles()
+
+    Clears the list of recent files. Should only be called by
+    the core plugin when the user chooses to clear it.
+*/
+void FileManager::clearRecentFiles()
+{
+    d->m_recentFiles.clear();
+}
+
 /*!
     \fn QStringList FileManager::recentFiles() const