nodeview: implemented copying/pasting nodes

Re-uses XML-based project saving/loading functions to store nodes, their
parameters, and their connections in a text-based format in the clipboard.

app/node/input.cpp

@@ -26,7 +26,7 @@
 
 #include "common/bezier.h"
 #include "common/lerp.h"
-#include "common/xmlreadloop.h"
+#include "common/xmlutils.h"
 #include "node.h"
 #include "output.h"
 #include "inputarray.h"

app/node/inputarray.cpp

@@ -2,7 +2,7 @@
 
 #include <QApplication>
 
-#include "common/xmlreadloop.h"
+#include "common/xmlutils.h"
 #include "node.h"
 
 NodeInputArray::NodeInputArray(const QString &id, const DataType &type, const QVariant &default_value) :

app/node/node.cpp

@@ -24,7 +24,7 @@
 #include <QDebug>
 #include <QFile>
 
-#include "common/xmlreadloop.h"
+#include "common/xmlutils.h"
 
 Node::Node() :
   can_be_deleted_(true)

app/node/output.cpp

@@ -20,7 +20,7 @@
 
 #include "output.h"
 
-#include "common/xmlreadloop.h"
+#include "common/xmlutils.h"
 #include "node/node.h"
 
 NodeOutput::NodeOutput(const QString &id) :