added save functions to various classes

Each class is responsible for its own saving and loading from the XML data
in order to reduce the complexity of the save code.

app/node/input.cpp

@@ -84,11 +84,63 @@ QString NodeInput::name()
   return NodeParam::name();
 }
 
+void NodeInput::Save(QXmlStreamWriter *writer) const
+{
+  writer->writeStartElement("input");
+
+  writer->writeAttribute("id", id());
+
+  writer->writeAttribute("ptr", QString::number(reinterpret_cast<quintptr>(this)));
+
+  writer->writeAttribute("keyframing", QString::number(keyframing_));
+
+  // Write standard value
+  writer->writeStartElement("standard");
+
+  foreach (const QVariant& v, standard_value_) {
+    writer->writeTextElement("value", v.toString());
+  }
+
+  writer->writeEndElement(); // standard
+
+  // Write keyframes
+  writer->writeStartElement("keyframes");
+
+  foreach (const KeyframeTrack& track, keyframe_tracks()) {
+    writer->writeStartElement("track");
+
+    foreach (NodeKeyframePtr key, track) {
+      writer->writeStartElement("key");
+
+      writer->writeAttribute("time", key->time().toString());
+      writer->writeAttribute("type", QString::number(key->type()));
+
+      writer->writeCharacters(key->value().toString());
+
+      writer->writeEndElement(); // key
+    }
+
+    writer->writeEndElement(); // track
+  }
+
+  writer->writeEndElement(); // keyframes
+
+  SaveConnections(writer);
+
+  SaveInternal(writer);
+
+  writer->writeEndElement(); // input
+}
+
 const NodeParam::DataType &NodeInput::data_type() const
 {
   return data_type_;
 }
 
+void NodeInput::SaveInternal(QXmlStreamWriter *writer) const
+{
+}
+
 NodeOutput *NodeInput::get_connected_output() const
 {
   if (!edges_.isEmpty()) {