Optimise imports

1. imports from std
2. imports from external crates
3. imports from local modules
4. imports from self

src/output/details.rs

@@ -113,24 +113,15 @@
 
 use std::error::Error;
 use std::io;
+use std::iter::repeat;
+use std::ops::Add;
 use std::path::PathBuf;
 use std::string::ToString;
-use std::ops::Add;
-use std::iter::repeat;
-
-use dir::Dir;
-use feature::xattr::{Attribute, FileAttributes};
-use file::fields as f;
-use file::File;
-use options::{FileFilter, RecurseOptions};
-use output::colours::Colours;
-use output::column::{Alignment, Column, Columns, SizeFormat};
-use output::cell::{TextCell, DisplayWidth};
 
 use ansi_term::Style;
 
-use datetime::local::{LocalDateTime, DatePiece};
 use datetime::format::DateFormat;
+use datetime::local::{LocalDateTime, DatePiece};
 use datetime::zoned::TimeZone;
 
 use locale;
@@ -138,6 +129,14 @@ use locale;
 use users::{OSUsers, Users};
 use users::mock::MockUsers;
 
+use dir::Dir;
+use feature::xattr::{Attribute, FileAttributes};
+use file::fields as f;
+use file::File;
+use options::{FileFilter, RecurseOptions};
+use output::colours::Colours;
+use output::column::{Alignment, Column, Columns, SizeFormat};
+use output::cell::{TextCell, DisplayWidth};
 use super::filename;