Obnam: tidying up

Goal Today I will tidy up various small things. Plan Add clippy lints to prevent many causes of panic. Change chunk labels to be URL friendly in the same way identifiers are. Notes Enabled clippy lints: clippy::panic clippy::panicking_unwrap clippy::unwrap_in_result clippy::unwrap_used This required fixing many places, but all straightforward. Most annoying part of this is that the lints are meant…