Update dependencies. Remove codegen

[gpoitch]

• Updates all dependencies & peer requirements
• Removes codegen feature which was outdated (and unadvertised?). (Separate concern IMO)
• Replace yarn.lock with package-lock.json

Note: I un-gitignored lib/ so I can use this git fork. Should undo that if this gets accepted.

[dios-david]

@stephen hey, can this be merged please?

[weotch]

Agreed, this solved some issues for me when this package was a dependency of another package.