Switch to 2018 edition

Most of this was generated by the absolutely extraordinary `cargo fix`
subcommand. There were still 2 errors and a few warnings to patch up,
but compared to the normal 600+ errors, I'd say the fixer did a damn
good job! I'm also amazed that I could still start the VM after this,
I half expected some kinds of runtime failure...

src/scheme/sys/context.rs

@@ -2,8 +2,8 @@ use alloc::string::String;
 use alloc::vec::Vec;
 use core::str;
 
-use context;
-use syscall::error::Result;
+use crate::context;
+use crate::syscall::error::Result;
 
 pub fn resource() -> Result<Vec<u8>> {
     let mut string = format!("{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<6}{:<8}{}\n",

src/scheme/sys/cpu.rs

@@ -1,10 +1,10 @@
 use alloc::vec::Vec;
 
-use device::cpu::cpu_info;
-use syscall::error::{Error, EIO, Result};
+use crate::device::cpu::cpu_info;
+use crate::syscall::error::{Error, EIO, Result};
 
 pub fn resource() -> Result<Vec<u8>> {
-    let mut string = format!("CPUs: {}\n", ::cpu_count());
+    let mut string = format!("CPUs: {}\n", crate::cpu_count());
 
     match cpu_info(&mut string) {
         Ok(()) => Ok(string.into_bytes()),

src/scheme/sys/exe.rs

@@ -1,7 +1,7 @@
 use alloc::vec::Vec;
 
-use context;
-use syscall::error::{Error, ESRCH, Result};
+use crate::context;
+use crate::syscall::error::{Error, ESRCH, Result};
 
 pub fn resource() -> Result<Vec<u8>> {
     let mut name = {

src/scheme/sys/iostat.rs

@@ -3,9 +3,9 @@ use alloc::vec::Vec;
 use core::fmt::Write;
 use core::str;
 
-use context;
-use scheme;
-use syscall::error::Result;
+use crate::context;
+use crate::scheme;
+use crate::syscall::error::Result;
 
 pub fn resource() -> Result<Vec<u8>> {
     let mut string = String::new();

src/scheme/sys/log.rs

@@ -1,7 +1,7 @@
 use alloc::vec::Vec;
 
-use log::LOG;
-use syscall::error::Result;
+use crate::log::LOG;
+use crate::syscall::error::Result;
 
 pub fn resource() -> Result<Vec<u8>> {
     let mut vec = Vec::new();

src/scheme/sys/mod.rs

@@ -5,10 +5,10 @@ use core::{cmp, str};
 use core::sync::atomic::{AtomicUsize, Ordering};
 use spin::RwLock;
 
-use syscall::data::Stat;
-use syscall::error::{Error, EBADF, EINVAL, ENOENT, Result};
-use syscall::flag::{MODE_DIR, MODE_FILE, SEEK_CUR, SEEK_END, SEEK_SET};
-use syscall::scheme::Scheme;
+use crate::syscall::data::Stat;
+use crate::syscall::error::{Error, EBADF, EINVAL, ENOENT, Result};
+use crate::syscall::flag::{MODE_DIR, MODE_FILE, SEEK_CUR, SEEK_END, SEEK_SET};
+use crate::syscall::scheme::Scheme;
 
 mod context;
 mod cpu;

src/scheme/sys/scheme.rs

@@ -1,8 +1,8 @@
 use alloc::vec::Vec;
 
-use context;
-use scheme;
-use syscall::error::{Error, ESRCH, Result};
+use crate::context;
+use crate::scheme;
+use crate::syscall::error::{Error, ESRCH, Result};
 
 pub fn resource() -> Result<Vec<u8>> {
     let scheme_ns = {

src/scheme/sys/scheme_num.rs

@@ -1,8 +1,8 @@
 use alloc::vec::Vec;
 
-use context;
-use scheme;
-use syscall::error::{Error, ESRCH, Result};
+use crate::context;
+use crate::scheme;
+use crate::syscall::error::{Error, ESRCH, Result};
 
 pub fn resource() -> Result<Vec<u8>> {
     let scheme_ns = {

src/scheme/sys/syscall.rs

@@ -3,9 +3,9 @@ use alloc::vec::Vec;
 use core::fmt::Write;
 use core::str;
 
-use context;
-use syscall;
-use syscall::error::Result;
+use crate::context;
+use crate::syscall;
+use crate::syscall::error::Result;
 
 pub fn resource() -> Result<Vec<u8>> {
     let mut string = String::new();

src/scheme/sys/uname.rs

@@ -1,5 +1,5 @@
 use alloc::vec::Vec;
-use syscall::error::Result;
+use crate::syscall::error::Result;
 
 pub fn resource() -> Result<Vec<u8>> {
     Ok(format!("Redox\n\n{}\n\n{}\n",