Ensure a newline exists at the end of files.

Fixes #42.

_tools/exercise/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"fmt"
 	"io/ioutil"
+	"os"
 
 	"github.com/alecthomas/chroma/formatters"
 	"github.com/alecthomas/chroma/lexers"
@@ -24,12 +25,14 @@ func main() {
 			fmt.Printf("warning: could not find lexer for %q\n", file)
 			continue
 		}
+		fmt.Printf("%s: ", file)
+		os.Stdout.Sync()
 		text, err := ioutil.ReadFile(file)
 		kingpin.FatalIfError(err, "")
 		it, err := lexer.Tokenise(nil, string(text))
 		kingpin.FatalIfError(err, "%s failed to tokenise %q", lexer.Config().Name, file)
 		err = formatters.NoOp.Format(ioutil.Discard, styles.SwapOff, it)
 		kingpin.FatalIfError(err, "%s failed to format %q", lexer.Config().Name, file)
-		fmt.Printf("ok: %q\n", file)
+		fmt.Printf("ok\n")
 	}
 }