Rewrite module declarations that use the `#[path="…"]` annotation
to the more idomatic `pub mod …` + `pub use …` forms.
For the "self" module, that is not possible because `self` is an
identifier in Rust, and also `r#self` is not admissable as a raw
identifier, so stick to `rad_self`.
Files in submodules were patched as appropriate.
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