Notify preprocessors of the mdbook version and add __non_exhaustive elements

* Updated the documentation for new preprocessor format

* adjusted the descriptions for preprocessors

src/lib.rs

@@ -114,6 +114,12 @@ pub mod renderer;
 pub mod theme;
 pub mod utils;
 
+/// The current version of `mdbook`.
+///
+/// This is provided as a way for custom preprocessors and renderers to do
+/// compatibility checks.
+pub const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
+
 pub use book::BookItem;
 pub use book::MDBook;
 pub use config::Config;

src/preprocess/mod.rs

@@ -21,12 +21,21 @@ pub struct PreprocessorContext {
     pub config: Config,
     /// The `Renderer` this preprocessor is being used with.
     pub renderer: String,
+    /// The calling `mdbook` version.
+    pub mdbook_version: String,
+    __non_exhaustive: (),
 }
 
 impl PreprocessorContext {
     /// Create a new `PreprocessorContext`.
     pub(crate) fn new(root: PathBuf, config: Config, renderer: String) -> Self {
-        PreprocessorContext { root, config, renderer }
+        PreprocessorContext {
+            root,
+            config,
+            renderer,
+            mdbook_version: ::MDBOOK_VERSION.to_string(),
+            __non_exhaustive: (),
+        }
     }
 }
 

src/renderer/mod.rs

@@ -26,8 +26,6 @@ use book::Book;
 use config::Config;
 use errors::*;
 
-const MDBOOK_VERSION: &str = env!("CARGO_PKG_VERSION");
-
 /// An arbitrary `mdbook` backend.
 ///
 /// Although it's quite possible for you to import `mdbook` as a library and
@@ -66,6 +64,7 @@ pub struct RenderContext {
     /// renderers to cache intermediate results, this directory is not
     /// guaranteed to be empty or even exist.
     pub destination: PathBuf,
+    __non_exhaustive: (),
 }
 
 impl RenderContext {
@@ -78,9 +77,10 @@ impl RenderContext {
         RenderContext {
             book: book,
             config: config,
-            version: MDBOOK_VERSION.to_string(),
+            version: ::MDBOOK_VERSION.to_string(),
             root: root.into(),
             destination: destination.into(),
+            __non_exhaustive: (),
         }
     }
 

src/theme/index.hbs

@@ -27,7 +27,7 @@
 
         <!-- Custom theme stylesheets -->
         {{#each additional_css}}
-        <link rel="stylesheet" href="{{ this }}">
+        <link rel="stylesheet" href="{{ ../path_to_root }}{{ this }}">
         {{/each}}
 
         {{#if mathjax_support}}
@@ -235,7 +235,7 @@
 
         <!-- Custom JS scripts -->
         {{#each additional_js}}
-        <script type="text/javascript" src="{{ path_to_root }}{{this}}"></script>
+        <script type="text/javascript" src="{{ ../path_to_root }}{{this}}"></script>
         {{/each}}
 
         {{#if is_print}}