[VoxBo] Finding geometric center

[Daniel Kimberg]

David January wrote:
> I think it's still buggy...

vbregion previously used >= for the threshold, so with a default threshold of 0, all 0 voxels would be included.  Not that helpful -- the bogus center you were getting was just the center of the whole volume.  I just changed it to default to >0, and now both the -t and -a flags use >, not >=.

I also changed it to issue a warning if it can't find voxel sizes, and in that case give origin-relative coordinates in voxels.

dan