Removing object offsets storage?

[Luke-Poeppel]

When I first started writing get_object_indices, I stored both the extracted objects and the (offset, offset+quarterLength) pair. But this is pretty silly... It's stored in the object anyway! It is slightly more safe because of the contiguous summation stuff, but if I'm appropriately deepcopying it, it really shouldn't be necessary. Moreover, removing the lists consequently removes all the confusing obj[1][0], obj[-1][1] stuff.