remove object store

[Licini]

Not done @tomvanmele just for you to compare, if you run this

from compas.scene import Scene
from compas.geometry import Box
from compas import json_dumps

scene = Scene()

box = Box(1, 1, 1)
obj1 = scene.add(box, name="BoxObj1")
obj2 = scene.add(box, name="BoxObj2", parent=obj1)

print(scene)

json_str = json_dumps(scene, pretty=True)
print(json_str)

You will get serialization like:

└── <TreeNode: Scene>
    └── BoxObj1
        └── BoxObj2
{
    "data": {
        "attributes": {},
        "datastore": {
            "86a97961-b36e-461e-a77f-eddaf07ae697": {
                "data": {
                    "frame": {
                        "point": [
                            0.0,
                            0.0,
                            0.0
                        ],
                        "xaxis": [
                            1.0,
                            0.0,
                            0.0
                        ],
                        "yaxis": [
                            0.0,
                            1.0,
                            0.0
                        ]
                    },
                    "xsize": 1.0,
                    "ysize": 1.0,
                    "zsize": 1.0
                },
                "dtype": "compas.geometry/Box",
                "guid": "86a97961-b36e-461e-a77f-eddaf07ae697"
            }
        },
        "name": "Scene",
        "tree": {
            "data": {
                "attributes": {},
                "root": {
                    "children": [
                        {
                            "children": [
                                {
                                    "color": null,
                                    "item": "86a97961-b36e-461e-a77f-eddaf07ae697",
                                    "name": "BoxObj2",
                                    "opacity": 1.0,
                                    "show": true,
                                    "transformation": null
                                }
                            ],
                            "color": null,
                            "item": "86a97961-b36e-461e-a77f-eddaf07ae697",
                            "name": "BoxObj1",
                            "opacity": 1.0,
                            "show": true,
                            "transformation": null
                        }
                    ],
                    "name": "Scene"
                }
            },
            "dtype": "compas.datastructures/Tree",
            "guid": "1d28f541-1e02-40b0-acf5-977319d71237",
            "inheritance": []
        }
    },
    "dtype": "compas.scene/Scene",
    "guid": "ac425fa8-2a6d-4fd1-9036-77cf97a8716e",
    "inheritance": []
}