Rename list's "car"/"cdr" to "head"/"tail"

[kud1ing]

I think the meaning of "head" and "tail" would be easier to guess and remember.

Also recent languages such as Haskell ("head", "tail"), OCaml ("hd", "tl") and F# ("Head", "Tail") tend to prefer those more literal names.

[brson]

I agree, and it would match what we have in std::vec