Qt Creator Plugin HOWTO documentation first and second cut

Signed-off-by: Abhishek Patil <abhishek.patil@vcreatelogic.com>

Merge-request: 145
Reviewed-by: con <qtc-committer@nokia.com>

doc/examples/dirmodelplugin/dirmodelpluginplugin.cpp

@@ -0,0 +1,35 @@
+#include "dirmodelpluginplugin.h"
+
+#include <QtPlugin>
+#include <QStringList>
+#include "DirNavigationFactory.h"
+
+DirModelPluginPlugin::DirModelPluginPlugin()
+{
+    // Do nothing
+}
+
+DirModelPluginPlugin::~DirModelPluginPlugin()
+{
+    // Do notning
+}
+
+void DirModelPluginPlugin::extensionsInitialized()
+{
+    // Do nothing
+}
+
+bool DirModelPluginPlugin::initialize(const QStringList& args, QString *errMsg)
+{
+    Q_UNUSED(args);
+    Q_UNUSED(errMsg);
+    addAutoReleasedObject(new DirNavigationFactory);
+    return true;
+}
+
+void DirModelPluginPlugin::shutdown()
+{
+    // Do nothing
+}
+
+Q_EXPORT_PLUGIN(DirModelPluginPlugin)