improve performance of solid voxelization, now for a 64x64x64 grid, the time for filling inside voxels are 0.20s(13% of total) and 0.36s(3% of total) for the bunny and buddha model respectively
improve performance of solid voxelization, now for a 64x64x64 grid, the time for filling inside voxels are 0.20s(13% of total) and 0.36s(3% of total) for the bunny and buddha model respectively

dajusc/trimesh,dajusc/trimesh,mikedh/trimesh,mikedh/trimesh,mikedh/trimesh,mikedh/trimesh