- Made some methods public, if they seemed like they'd be useful crates that depend on plonky2, and seemed like good/stable APIs
- Deleted a few things I didn't think seemed very useful
- Left a few for now that I was on the fence about
It's just a wrapper around `Target`, which signifies that the wrapped `Target` has already been range checked. Should make it easier to audit code that expects bools.
No functional changes here. The biggest change was moving certain files into new directories like `plonk` and `iop` (for things like `Challenger` that could be used in STARKs or other IOPs). I also split a few files, renames, etc, but again nothing functional, so I don't think a careful review is necessary (just a sanity check).
* Have add_gate take a generic type instead of GateRef
There are a couple advantages
- Users writing their own gates won't need to know about the `GateRef` wrapper; it's more of an internal thing now.
- Easier access to gate methods requiring `self` -- for example, `split_le_base` can just call `gate_type.limbs()` now.
* Update comment
* Always insert
