timeline/project: block serializations to and from xml now include links

Fixes issue where blocks would become unlinked after copy/paste or save/load.

app/common/xmlutils.h

@@ -4,13 +4,14 @@
 #include <QUndoCommand>
 #include <QXmlStreamReader>
 
+#include "project/item/footage/stream.h"
+
+class Block;
 class Node;
 class NodeParam;
 class NodeInput;
 class NodeOutput;
 
-#include "project/item/footage/stream.h"
-
 #define XMLAttributeLoop(reader, item) \
   QXmlStreamAttributes __attributes = reader->attributes(); \
   foreach (const QXmlStreamAttribute& item, __attributes)
@@ -28,14 +29,23 @@ struct XMLNodeData {
     quintptr footage;
   };
 
+  struct BlockLink {
+    Block* block;
+    quintptr link;
+  };
+
   QHash<quintptr, NodeOutput*> output_ptrs;
   QList<SerializedConnection> desired_connections;
   QHash<quintptr, StreamPtr> footage_ptrs;
   QList<FootageConnection> footage_connections;
+  QList<BlockLink> block_links;
+
 };
 
-void XMLConnectNodes(const QHash<quintptr, NodeOutput *> &output_ptrs, const QList<XMLNodeData::SerializedConnection> &desired_connections, QUndoCommand* command = nullptr);
+void XMLConnectNodes(const XMLNodeData& xml_node_data, QUndoCommand* command = nullptr);
 
 bool XMLReadNextStartElement(QXmlStreamReader* reader);
 
+void XMLLinkBlocks(const XMLNodeData& xml_node_data);
+
 #endif // XMLREADLOOP_H