hindent doesn't end a file with a newline

[jml]

Don't know if this is deliberate or not, but it was pretty surprising to me and my preference would be to end with a newline.

$ hindent --version
hindent 4.6.3
$ hindent --style johan-tibell < Main.hs  > Main.hs.new
$ diff -u Main.hs Main.hs.new
--- Main.hs 2016-08-18 20:21:50.000000000 +0100
+++ Main.hs.new 2016-08-18 20:21:59.000000000 +0100
@@ -20,4 +20,4 @@
         Right comments ->
             mapM_
                 (putStrLn . Fixme.formatTodo)
-                (concatMap Fixme.getTodos comments)
+                (concatMap Fixme.getTodos comments)
\ No newline at end of file

[chrisdone]

I'll add a check that says if the original input ends with a newline, then we output with a newline.