Can't decode str in python3

Hey :)

I am encountering an error when loading meshes from the h5 files:
```
line 371, in load_mesh
    mesh_fname = data["object/file"][()].decode('utf-8')
AttributeError: 'str' object has no attribute 'decode'
```

In Python3, strings are already unicode objects, so dropping `.decode('utf-8')` resolves the error for me.