Can't create shapes with int size

[paulmelnikow]

Via lacecore:

>>> from lacecore import shapes
>>> m = shapes.cube(origin=np.zeros(3), size=1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Users/pnm/code/purl-anatomia/.venv/lib/python3.7/site-packages/lacecore/shapes/_shapes.py", line 50, in cube
    return _mesh_from_shape_fn(shapes.cube, origin=origin, size=size)
  File "/Users/pnm/code/purl-anatomia/.venv/lib/python3.7/site-packages/lacecore/shapes/_shapes.py", line 14, in _mesh_from_shape_fn
    *args, ret_unique_vertices_and_faces=True, **kwargs
  File "/Users/pnm/code/purl-anatomia/.venv/lib/python3.7/site-packages/polliwog/shapes/_shapes.py", line 102, in cube
    raise ValueError("`size` should be a number")
ValueError: `size` should be a number