Request: Orientation-dependent shift values

[MostlyNumbers]

This may not be a lunch break implementation, but it would be great, creatively, to have access to sprite shift values that are rotationally dependent (ie an array of 64 shift values). This would allow, for instance, vehicles with off-center or multiple turrets.

This kind of already exists with the artillery turret's cannon_base_shiftings, so might not be completely from scratch?