explicitly destroy NodeParams in Node destructor

NodeParams used to be destroyed automatically through the QObject system, but
now that NodeParams perform actions that access the parent Node object in
their destructor, the NodeParam destructor needs to be called before the Node
has been fully destroyed. By destroying explicitly in the Node destructor we
accomplish this.

app/node/node.cpp

@@ -28,6 +28,15 @@ Node::Node() :
 {
 }
 
+Node::~Node()
+{
+  // We delete in the Node destructor rather than relying on the QObject system because the parameter may need to
+  // perform actions on this Node object and we want them to be done before the Node object is fully destroyed
+  foreach (NodeParam* param, params_) {
+    delete param;
+  }
+}
+
 QString Node::Category()
 {
   // Return an empty category for any nodes that don't use one
@@ -234,6 +243,11 @@ bool Node::IsBlock()
   return false;
 }
 
+bool Node::IsTrack()
+{
+  return false;
+}
+
 rational Node::LastProcessedTime()
 {
   rational t;