EffectChain: remember original effect plugin data when loading dummy plugin

We don't want to loose the settings of an effect plugin even if it's not
available and thus can't be instantiated. Therefore remember original
settings data and save them back properly.

Partly closes #733.

include/DummyEffect.h

@@ -82,9 +82,10 @@ public:
 class DummyEffect : public Effect
 {
 public:
-	DummyEffect( Model * _parent ) :
+	DummyEffect( Model * _parent, const QDomElement& originalPluginData ) :
 		Effect( NULL, _parent, NULL ),
-		m_controls( this )
+		m_controls( this ),
+		m_originalPluginData( originalPluginData )
 	{
 	}
 
@@ -102,9 +103,16 @@ public:
 		return false;
 	}
 
+	const QDomElement& originalPluginData() const
+	{
+		return m_originalPluginData;
+	}
+
+
 
 private:
 	DummyEffectControls m_controls;
+	const QDomElement m_originalPluginData;
 
 } ;