deprecate Unicode functions that will be moved to crates.io

This patch
1. renames libunicode to librustc_unicode,
2. deprecates several pieces of libunicode (see below), and
3. removes references to deprecated functions from
   librustc_driver and libsyntax. This may change pretty-printed
   output from these modules in cases involving wide or combining
   characters used in filenames, identifiers, etc.

The following functions are marked deprecated:

1. char.width() and str.width():
   --> use unicode-width crate

2. str.graphemes() and str.grapheme_indices():
   --> use unicode-segmentation crate

3. str.nfd_chars(), str.nfkd_chars(), str.nfc_chars(), str.nfkc_chars(),
   char.compose(), char.decompose_canonical(), char.decompose_compatible(),
   char.canonical_combining_class():
   --> use unicode-normalization crate

src/librustc_driver/lib.rs

@@ -35,7 +35,6 @@
 #![feature(staged_api)]
 #![feature(exit_status)]
 #![feature(set_stdio)]
-#![feature(unicode)]
 
 extern crate arena;
 extern crate flate;
@@ -574,7 +573,7 @@ Available lint options:
     let builtin_groups = sort_lint_groups(builtin_groups);
 
     let max_name_len = plugin.iter().chain(builtin.iter())
-        .map(|&s| s.name.width(true))
+        .map(|&s| s.name.chars().count())
         .max().unwrap_or(0);
     let padded = |x: &str| {
         let mut s = repeat(" ").take(max_name_len - x.chars().count())
@@ -601,7 +600,7 @@ Available lint options:
 
 
     let max_name_len = plugin_groups.iter().chain(builtin_groups.iter())
-        .map(|&(s, _)| s.width(true))
+        .map(|&(s, _)| s.chars().count())
         .max().unwrap_or(0);
     let padded = |x: &str| {
         let mut s = repeat(" ").take(max_name_len - x.chars().count())
@@ -790,7 +789,6 @@ fn parse_crate_attrs(sess: &Session, input: &Input) ->
 ///
 /// The diagnostic emitter yielded to the procedure should be used for reporting
 /// errors of the compiler.
-#[allow(deprecated)]
 pub fn monitor<F:FnOnce()+Send+'static>(f: F) {
     const STACK_SIZE: usize = 8 * 1024 * 1024; // 8MB