WIP: Adding scalars and scalar indexing

[dgkf]

For now this is just a placeholder PR so that I don't lose some code I wrote up on the train a while back. Once things are properly working I'll revise with a more thoughtful description of the changes.

TODO

• Strip out these release binary related commits. Will need to investigate how they snuck in here - my suspicion is that I had some lingering commits on main on my laptop that got rebased onto main when I kicked off this branch.