Update to Rust 2018 edition (#632)

* initial cargo fix run

* Upgrade cranelift-entity crate

* Upgrade bforest crate

* Upgrade the codegen crate

* Upgrade the faerie crate

* Upgrade the filetests crate

* Upgrade the codegen-meta crate

* Upgrade the frontend crate

* Upgrade the cranelift-module crate

* Upgrade the cranelift-native crate

* Upgrade the cranelift-preopt crate

* Upgrade the cranelift-reader crate

* Upgrade the cranelift-serde crate

* Upgrade the cranelift-simplejit crate

* Upgrade the cranelift or cranelift-umbrella crate

* Upgrade the cranelift-wasm crate

* Upgrade cranelift-tools crate

* Use new import style on remaining files

* run format-all.sh

* run test-all.sh, update Readme and travis ci configuration
fixed an AssertionError also

* Remove deprecated functions

lib/bforest/src/lib.rs

@@ -48,7 +48,7 @@ mod std {
 
 #[macro_use]
 extern crate cranelift_entity as entity;
-use entity::packed_option;
+use crate::entity::packed_option;
 
 use std::borrow::BorrowMut;
 use std::cmp::Ordering;
@@ -157,7 +157,7 @@ fn slice_shift<T: Copy>(s: &mut [T], n: usize) {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use entity::EntityRef;
+    use crate::entity::EntityRef;
 
     /// An opaque reference to an extended basic block in a function.
     #[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]

lib/bforest/src/map.rs

@@ -1,7 +1,7 @@
 //! Forest of maps.
 
 use super::{Comparator, Forest, Node, NodeData, NodePool, Path, INNER_SIZE};
-use packed_option::PackedOption;
+use crate::packed_option::PackedOption;
 #[cfg(test)]
 use std::fmt;
 use std::marker::PhantomData;

lib/bforest/src/pool.rs

@@ -3,7 +3,7 @@
 #[cfg(test)]
 use super::Comparator;
 use super::{Forest, Node, NodeData};
-use entity::PrimaryMap;
+use crate::entity::PrimaryMap;
 #[cfg(test)]
 use std::fmt;
 use std::ops::{Index, IndexMut};
@@ -83,7 +83,7 @@ impl<F: Forest> NodePool<F> {
         NodeData<F>: fmt::Display,
         F::Key: fmt::Display,
     {
-        use entity::SparseSet;
+        use crate::entity::SparseSet;
         use std::borrow::Borrow;
         use std::cmp::Ordering;
         use std::vec::Vec;

lib/bforest/src/set.rs

@@ -1,7 +1,7 @@
 //! Forest of sets.
 
 use super::{Comparator, Forest, Node, NodeData, NodePool, Path, SetValue, INNER_SIZE};
-use packed_option::PackedOption;
+use crate::packed_option::PackedOption;
 #[cfg(test)]
 use std::fmt;
 use std::marker::PhantomData;