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/codegen/meta-python/gen_instr.py

@@ -661,7 +661,7 @@ def gen_inst_builder(inst, fmt):
     # The controlling type variable will be inferred from the input values if
     # possible. Otherwise, it is the first method argument.
     if inst.is_polymorphic and not inst.use_typevar_operand:
-        args.append('{}: ir::Type'.format(inst.ctrl_typevar.name))
+        args.append('{}: crate::ir::Type'.format(inst.ctrl_typevar.name))
 
     tmpl_types = list()  # type: List[str]
     into_args = list()  # type: List[str]