Group, Transform, AttributeState : Remove

These are no longer useful for rendering because the Renderer class has gone. And they've not useful in Gaffer because it represents grouping, transform and attributes using a different mechanism.

Author: johnhaddon

Changes

@@ -15,7 +15,7 @@ Breaking Changes
 - Renderable : Removed `render()` method.
 - CoordinateSystem : Removed transform.
 - Font : Removed `meshGroup()` method.
-- Options : Removed.
+- Options, Group, Transform, MatrixTransform, MatrixMotionTransform, AttributeState : Removed.
 - CurveExtrudeOp, IDXReader : Removed.
 - Renderer, AttributeBlock, EditBlock, MotionBlock, TransformBlock, WorldBlock : Removed.
 - IECoreHoudini : Removed.

contrib/IECoreAlembic/src/IECoreAlembic/CameraReader.cpp

@@ -36,7 +36,6 @@
 #include "IECoreAlembic/ObjectReader.h"
 
 #include "IECoreScene/Camera.h"
-#include "IECoreScene/Transform.h"
 
 #include "IECore/SimpleTypedData.h"