Use clippy (#276)

* cton-util: fix some clippy unnecessary pass-by-value warnings

* clippy: ignore too many arguments / cyclomatic complexity in module

since these functions are taking args coming from the command line, i
dont think this is actually a valid lint, morally the arguments are all
from one structure

* cton-util: take care of remaining clippy warnings

* cton-reader: fix all non-suspicious clippy warnings

* cton-reader: disable clippy at site of suspicious lint

* cton-frontend: disable clippy at the site of an invalid lint

* cton-frontend: fix clippy warnings, or ignore benign ones

* clippy: ignore the camelcase word WebAssembly in docs

* cton-wasm: fix clippy complaints or ignore benign ones

* cton-wasm tests: fix clippy complaints

* cretonne: starting point turns off all clippy warnings

* cretonne: clippy fixes, or lower allow() to source of problem

* cretonne: more clippy fixes

* cretonne: fix or disable needless_lifetimes lint

this linter is buggy when the declared lifetime is used for another type
constraint.

* cretonne: fix clippy complaint about Pass::NoPass

* rustfmt

* fix prev minor api changes clippy suggested

* add clippy to test-all

* cton-filetests: clippy fixes

* simplify clippy reporting in test-all

* cretonne: document clippy allows better

* cretonne: fix some more clippy lints

* cretonne: fix clippy lints (mostly doc comments)

* cretonne: allow all needless_lifetimes clippy warnings

remove overrides at the false positives

* rustfmt

cranelift/src/cat.rs

@@ -7,7 +7,7 @@ use cton_reader::parse_functions;
 use CommandResult;
 use utils::read_to_string;
 
-pub fn run(files: Vec<String>) -> CommandResult {
+pub fn run(files: &[String]) -> CommandResult {
     for (i, f) in files.into_iter().enumerate() {
         if i != 0 {
             println!();
@@ -17,7 +17,7 @@ pub fn run(files: Vec<String>) -> CommandResult {
     Ok(())
 }
 
-fn cat_one(filename: String) -> CommandResult {
+fn cat_one(filename: &str) -> CommandResult {
     let buffer = read_to_string(&filename).map_err(
         |e| format!("{}: {}", filename, e),
     )?;