Fixes for the liburl changes

This makes the library compilable after rust-lang/rust@b8ef5cf1310a7b1e31d0993885d867a6804597ad, which introduced a number of breaking changes to `liburl`.

While I was at it, I also solved the warnings about the deprecated `#![crate_id]` attribute, and substituted it for the newer `#![crate_name]`