dynamic registration

[casperdcl]

Need amypet <- nimpa <- spm12 dependency for registration.

Dynamic

0. moving average batches
1. coregister all permutations; use minimum distance as ref
2. sum all and use as new ref
3. coregister to ref
4. automatically split whole scan into two batches: early & late images

• weights based on counts & registration uncerts?
• start with accepted methods first :)
  • 10 min frames (not moving avg) for [¹⁸F]