ordered indexing for integers

I was looking at adding support for ordered indexing for Integer attributes. This would be an incompatible format change for index databases. In fact I'd need to change the Presence index key as well, so it would affect all index databases, not just those for Integer attributes.

Currently the Presence index uses a hardcoded 4 byte key of 0x00000001. I want to change it to a 2 byte key of 0x0000 instead, to prevent it from colliding with the Integer key space.

So far, 2.4 and 2.3 have totally identical database formats. Is it worthwhile to break this compatibility to gain this feature, or better to preserve compatibility and ignore this feature for now? Any thoughts on going ahead with it here in RE24?