Transition to 2018 edition (#933)

* Transition to 2018 edition

* Update Travis CI badge in README

* Remove non-idiomatic `extern crate` lines

4 files changed, 11 insertions, 13 deletions

diff --git a/src/book/book.rs b/src/book/book.rs
index f4870f1f..6a31c9e8 100644
--- a/src/book/book.rs
+++ b/src/book/book.rs
@@ -5,8 +5,8 @@ use std::io::{Read, Write};
 use std::path::{Path, PathBuf};
 
 use super::summary::{parse_summary, Link, SectionNumber, Summary, SummaryItem};
-use config::BuildConfig;
-use errors::*;
+use crate::config::BuildConfig;
+use crate::errors::*;
 
 /// Load a book into memory from its `src/` directory.
 pub fn load_book<P: AsRef<Path>>(src_dir: P, cfg: &BuildConfig) -> Result<Book> {
diff --git a/src/book/init.rs b/src/book/init.rs
index a70006bb..f940e1fa 100644
--- a/src/book/init.rs
+++ b/src/book/init.rs
@@ -1,12 +1,11 @@
 use std::fs::{self, File};
 use std::io::Write;
 use std::path::PathBuf;
-use toml;
 
 use super::MDBook;
-use config::Config;
-use errors::*;
-use theme;
+use crate::config::Config;
+use crate::errors::*;
+use crate::theme;
 
 /// A helper for setting up a new book and its directory structure.
 #[derive(Debug, Clone, PartialEq)]
diff --git a/src/book/mod.rs b/src/book/mod.rs
index 040e7265..3b25c68e 100644
--- a/src/book/mod.rs
+++ b/src/book/mod.rs
@@ -20,14 +20,14 @@ use std::string::ToString;
 use tempfile::Builder as TempFileBuilder;
 use toml::Value;
 
-use errors::*;
-use preprocess::{
+use crate::errors::*;
+use crate::preprocess::{
     CmdPreprocessor, IndexPreprocessor, LinkPreprocessor, Preprocessor, PreprocessorContext,
 };
-use renderer::{CmdRenderer, HtmlHandlebars, RenderContext, Renderer};
-use utils;
+use crate::renderer::{CmdRenderer, HtmlHandlebars, RenderContext, Renderer};
+use crate::utils;
 
-use config::Config;
+use crate::config::Config;
 
 /// The object used to manage and build a book.
 pub struct MDBook {
@@ -124,7 +124,6 @@ impl MDBook {
     /// `(section: String, bookitem: &BookItem)`
     ///
     /// ```no_run
-    /// # extern crate mdbook;
     /// # use mdbook::MDBook;
     /// # use mdbook::book::BookItem;
     /// # #[allow(unused_variables)]
diff --git a/src/book/summary.rs b/src/book/summary.rs
index e61a3459..2c32cbd8 100644
--- a/src/book/summary.rs
+++ b/src/book/summary.rs
@@ -1,4 +1,4 @@
-use errors::*;
+use crate::errors::*;
 use memchr::{self, Memchr};
 use pulldown_cmark::{self, Event, Tag};
 use std::fmt::{self, Display, Formatter};