Clean up some remaining uses of mdbook_core

These should be using the appropriate high-level crate.

crates/mdbook-driver/src/mdbook.rs

@@ -140,7 +140,7 @@ impl MDBook {
     ///
     /// ```no_run
     /// # use mdbook_driver::MDBook;
-    /// # use mdbook_core::book::BookItem;
+    /// # use mdbook_driver::book::BookItem;
     /// # let book = MDBook::load("mybook").unwrap();
     /// for item in book.iter() {
     ///     match *item {

examples/nop-preprocessor.rs

@@ -37,14 +37,14 @@ fn handle_preprocessing(pre: &dyn Preprocessor) -> Result<()> {
     let (ctx, book) = mdbook_preprocessor::parse_input(io::stdin())?;
 
     let book_version = Version::parse(&ctx.mdbook_version)?;
-    let version_req = VersionReq::parse(mdbook_core::MDBOOK_VERSION)?;
+    let version_req = VersionReq::parse(mdbook_preprocessor::MDBOOK_VERSION)?;
 
     if !version_req.matches(&book_version) {
         eprintln!(
             "Warning: The {} plugin was built against version {} of mdbook, \
              but we're being called from version {}",
             pre.name(),
-            mdbook_core::MDBOOK_VERSION,
+            mdbook_preprocessor::MDBOOK_VERSION,
             ctx.mdbook_version
         );
     }

src/lib.rs

@@ -29,7 +29,7 @@
 //!
 //! ```rust,no_run
 //! use mdbook_driver::MDBook;
-//! use mdbook_core::config::Config;
+//! use mdbook_driver::config::Config;
 //!
 //! let root_dir = "/path/to/book/root";
 //!
@@ -78,4 +78,4 @@
 //! [user guide]: https://rust-lang.github.io/mdBook/
 //! [`RenderContext`]: mdbook_renderer::RenderContext
 //! [relevant chapter]: https://rust-lang.github.io/mdBook/for_developers/backends.html
-//! [`Config`]: mdbook_core::config::Config
+//! [`Config`]: mdbook_driver::config::Config