LiveSceneHolder: Add liveScene() to construct a LiveScene from C++ without requiring the knob (UI only + Python binding).

Author: lucienfostier

include/IECoreNuke/LiveSceneHolder.h

@@ -57,6 +57,7 @@ class IECORENUKE_API LiveSceneHolder : public DD::Image::GeoOp
 		virtual void knobs( DD::Image::Knob_Callback f );
 		virtual const char *Class() const;
 		virtual const char *node_help() const;
+		IECoreNuke::LiveScenePtr liveScene();
 
 	private :
 

src/IECoreNuke/LiveSceneHolder.cpp

@@ -36,6 +36,8 @@
 
 #include "IECoreNuke/LiveSceneKnob.h"
 
+#include "IECoreScene/SceneInterface.h"
+
 using namespace IECoreNuke;
 
 const DD::Image::Op::Description LiveSceneHolder::g_description( "ieLiveScene", build );
@@ -70,3 +72,8 @@ const char *LiveSceneHolder::node_help() const
 {
 	return "Holds cortex live scene on the \"scene\" knob.";
 }
+
+IECoreNuke::LiveScenePtr LiveSceneHolder::liveScene()
+{
+ 	return new IECoreNuke::LiveScene( this );
+}