Add voxelization test and improve voxelization implementation

[kephale]

The previous version of voxelization could introduce holes in locations where triangles were axis aligned. This PR aims to resolve that and introduce a long needed voxelization test.

The idea here is that the previous version just tested if triangles intersect the center of any given voxel, now we test the corners of the voxel.

This was motivated by this Zulip thread.