Support point objects without width & height.

[max-vogler]

When using Tiled's point object

An object without width or height is created:

Which fails during compilation:

Traceback (most recent call last):
  File "butano-tiled/bntmx.py", line 341, in <module>
    process(args.target, args.mapsdirs, args.build)
  File "butano-tiled/bntmx.py", line 293, in process
    converter = TMXConverter(target, tmx_filename)
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "butano-tiled/bntmx.py", line 64, in __init__
    self._objects = list(map(lambda layer_path: self._tmx.objects(layer_path), self._descriptor["objects"]))
                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "butano-tiled/bntmx.py", line 64, in <lambda>
    self._objects = list(map(lambda layer_path: self._tmx.objects(layer_path), self._descriptor["objects"]))
                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "butano-tiled/tmx.py", line 278, in objects
    item_x, item_y = _object_position(item_node)
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "butano-tiled/tmx.py", line 35, in _object_position
    x = int(object_node.get("x")) + int(object_node.get("width")) // 2
                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: int() argument must be a string, a bytes-like object or a real number, not 'NoneType'

[Kekun]

Thanks! Please merge your fix commit into the initial one and I'll merge it.

[max-vogler]

Done!