load PLY file can't load custom properties

[Xiaohei-Luo]

After I run the tests/example_custom_mesh_attributes.py, i successfully added some properties that named "v_attr" 、“vp_attr”、“f_attr” in a new ply files. the compare of two ply files like below:

However, After load this new ply file, I can't get those added properties when i use vertex_custom_scalar_attribute_array('v_attr')， i get an error:No valid per vertex scalar attribute named v_attr was found, and face_custom_scalar_attribute_array('f_attr')、vertex_custom_point_attribute_matrix('vp_attr') get the same error.

The same question #368