Python Support for Panels on Custom Nodes

In blender, panels can only be added to nodes defined in the source code, not with python. This seems to be because the current way panels are put into a layout using the UILayout.panel function does not allow for sockets to be placed inside. What I propose to fix this is adding a new type of panel such as bpy.types.NodePanel, which supports adding sockets, with an instance of it being used in the bpy.types.Node class with the name panel, as well as the bpy.types.NodePanel having bpy.types.NodeInputs and NodeOutputs instances as panel.inputs and panel.outputs, allowing sockets to be added. Below is an example of how it could be used.