All voxels are black while importing from OBJ file

[yllan]

I tried the latest build including PR #1 with the test file Laocoon Figure. However, the official build behaves differently from my build, the imported voxels are all black.

Steps to Reproduce

1. Download the VoxelEditor.app from the project page.
2. Download the Laocoon Figure OBJ file and decompress.
3. Import the obj file in VoxelEditor

Expected Result

The voxels should reflect the texture of MTL file, which is colourful.

Actual Result

The voxels are all black.

Configuration

I've tried it on Mac OS X 10.8 and 10.9, both have the same issue. I compiled with Xcode 6 against openframeworks/openFrameworks@f74ebcb.