Merge pull request #197 from rpearl/checkformat

Make check_format actually useful

tools/check_format.sh

-#!/bin/sh
+#!/usr/bin/env bash
 set -eu
 failed=0
 for fn in $(find . -name '*.cpp' -o -name '*.h'); do
-    $1 -style=file -output-replacements-xml $fn | grep -q "replacement offset" && { echo $fn "failed clang-format check"; failed=1; }
+    diff -u $fn <($1 -style=file $fn) || failed=1
 done
 
 if [ $failed -eq 0 ]; then