Detect bracket sets for HDR, panorama and focus stacking

A photographer asked for this by email, and it comes up often enough to track in the open.

When you cull, imagic should recognise frames that were shot as a set to be merged, and keep them together instead of treating them as near-duplicates:

• exposure brackets for HDR
• overlapping frames for a panorama
• focus-shift sequences for focus stacking

Today imagic groups bursts and near-identical frames, but it does not recognise these sets yet.

Which of the three do you shoot most, and with which camera? Reply here, it helps decide what to build first. I'll post updates in this thread as it moves.