clean up #![features]

For the most part, this commit removes the `collections` feature.
In some places I've removed other features where the effort to do
so was pretty low.

src/base64/base64.rs

@@ -1,5 +1,5 @@
 #![crate_name = "base64"]
-#![feature(box_syntax, collections, rustc_private)]
+#![feature(box_syntax, rustc_private)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -48,7 +48,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         optflag("h", "help", "display this help text and exit"),
         optflag("V", "version", "output version information and exit")
     ];
-    let matches = match getopts(args.tail(), &opts) {
+    let matches = match getopts(&args[1..], &opts) {
         Ok(m) => m,
         Err(e) => {
             crash!(1, "error: {}", e);

src/basename/basename.rs

@@ -1,5 +1,5 @@
 #![crate_name = "basename"]
-#![feature(collections, rustc_private)]
+#![feature(rustc_private)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -34,7 +34,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         getopts::optflag("V", "version", "output version information and exit"),
     ];
 
-    let matches = match getopts::getopts(args.tail(), &opts) {
+    let matches = match getopts::getopts(&args[1..], &opts) {
         Ok(m)  => m,
         Err(f) => crash!(1, "Invalid options\n{}", f)
     };

src/cat/cat.rs

@@ -1,7 +1,5 @@
 #![crate_name = "cat"]
-#![feature(collections, rustc_private)]
-
-#![feature(box_syntax, unsafe_destructor)]
+#![feature(rustc_private, box_syntax, unsafe_destructor)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -42,7 +40,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         getopts::optflag("h", "help", "display this help and exit"),
         getopts::optflag("V", "version", "output version information and exit"),
     ];
-    let matches = match getopts::getopts(args.tail(), &opts) {
+    let matches = match getopts::getopts(&args[1..], &opts) {
         Ok(m) => m,
         Err(f) => panic!("Invalid options\n{}", f)
     };

src/chroot/chroot.rs

@@ -1,5 +1,5 @@
 #![crate_name = "chroot"]
-#![feature(collections, rustc_private, path_ext)]
+#![feature(rustc_private, path_ext)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -57,7 +57,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         optflag("V", "version", "Show program's version")
     ];
 
-    let opts = match getopts(args.tail(), &options) {
+    let opts = match getopts(&args[1..], &options) {
         Ok(m) => m,
         Err(f) => {
             show_error!("{}", f);
@@ -195,7 +195,7 @@ fn set_groups_from_str(groups: &str) {
 
 fn set_user(user: &str) {
     if !user.is_empty() {
-        let user_id = get_pw_from_args(&vec!(String::from_str(user))).unwrap().pw_uid;
+        let user_id = get_pw_from_args(&vec!(user.to_string())).unwrap().pw_uid;
         let err = unsafe { setuid(user_id as libc::uid_t) };
         if err != 0 {
             crash!(1, "cannot set user to {}: {}", user, Error::last_os_error())

src/echo/echo.rs

@@ -1,5 +1,5 @@
 #![crate_name = "echo"]
-#![feature(rustc_private, str_char)]
+#![feature(rustc_private)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -94,7 +94,7 @@ fn parse_options(args: Vec<String>, options: &mut EchoOptions) -> Option<Vec<Str
             "-e" => options.escape = true,
             "-E" => options.escape = false,
             _ => {
-                if arg.len() > 1 && arg.char_at(0) == '-' {
+                if arg.len() > 1 && arg.chars().next().unwrap_or('_') == '-' {
                     let mut newopts = options.clone();
                     for ch in arg.chars().skip(1) {
                         match ch {

src/fmt/fmt.rs

@@ -1,4 +1,5 @@
 #![crate_name = "fmt"]
+#![feature(box_syntax,rustc_private,str_char,unicode,core)]
 
 /*
  * This file is part of `fmt` from the uutils coreutils package.
@@ -9,9 +10,6 @@
  * file that was distributed with this source code.
  */
 
-#![feature(box_syntax,core,rustc_private,collections,str_char,unicode)]
-
-extern crate core;
 extern crate getopts;
 extern crate rustc_unicode;
 extern crate unicode_width;
@@ -87,7 +85,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         getopts::optflag("h", "help", "Display this help message and exit.")
             ];
 
-    let matches = match getopts::getopts(args.tail(), &opts[..]) {
+    let matches = match getopts::getopts(&args[1..], &opts[..]) {
         Ok(m) => m,
         Err(f) => crash!(1, "{}\nTry `{} --help' for more information.", f, args[0])
     };

src/fmt/parasplit.rs

@@ -7,7 +7,7 @@
  * file that was distributed with this source code.
  */
 
-use core::iter::Peekable;
+use std::iter::Peekable;
 use std::io::{BufRead, Lines};
 use std::slice::Iter;
 use std::str::CharRange;

src/sync/sync.rs

@@ -1,5 +1,5 @@
 #![crate_name = "sync"]
-#![feature(collections, rustc_private)]
+#![feature(rustc_private)]
 
 /*
  * This file is part of the uutils coreutils package.
@@ -148,7 +148,7 @@ pub fn uumain(args: Vec<String>) -> i32 {
         optflag("V", "version", "output version information and exit")
     ];
 
-    let matches = match getopts(args.tail(), &options) {
+    let matches = match getopts(&args[1..], &options) {
         Ok(m) => { m }
         _ => { help(program, &options); return 1 }
     };