Exporting tracks from blender 2.80

[alex25]

adding something like

                bpy.ops.object.editmode_toggle()
                bpy.ops.mesh.separate(type='MATERIAL')

before 

                objlist = bpy.context.scene.collection.all_objects

joe_pack.from_mesh() seems to split the objects by material. it might act only on selected objects, so selecting all objects might be needed first (i had them all selected in blender). thanks. now i have to remember how surfaces work, etc.