Rename cratename -> crate_name
Rename cratename -> crate_name

This makes it consistent with rustc_session::Options.

graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust