Creating a new Item3D widget for use in EMScene3D

To create a new Item3D widget use must inherit from EMItem3D (you will need to import this class from emitem3d). EMItem3D is a new style class so you don't need to multiply inherit from object.

For exmaple: 

   1 class EMNewItem(EMItem3D):
   2     name = "myname"
   3     nodetype = "mynodetype"
   4     def __init__(self, parent=None, children=None, transform=None):
   5         if not Transform: transform=transform()
   6         EMItem3D.__init__(self,parent=parent,children=children,transform=transform)