#[deny(non_camel_case_types)] is too aggressive

[whitequark]

Specifically, there are snake_case names that cannot be converted into CamelCase (as interpreted by this lint) without losing semantics: anything that contains two numbers with a separator. E.g foo_4_20 does not have a CamelCase equivalent that's accepted by the lint but is not confusable with the conversion result of foo_420.

Originally discovered in rust-embedded/svd2rust#76.