slab iterator for multiband like sequences
prevent some kind of memory leaks
slab fixes
wip
fix slice order for multiband
add voxel size to stuff extracted
Merge branch 'online' into testing2

* online:
  add voxel size to stuff extracted
  fix slice order for multiband
  wip
  slab fixes
  prevent some kind of memory leaks
  slab iterator for multiband like sequences