Challenge: write a really really small front() for UTF8

[safety0ff]

On Sunday, 23 March 2014 at 21:23:18 UTC, Andrei Alexandrescu 
wrote:
> Here's a baseline: http://goo.gl/91vIGc. Destroy!
>
> Andrei

Here's my attempt: http://goo.gl/alJ9JS
I interpreted the challenge slightly differently, I went for 
fewer lines of code and fewer branches.

I verified the output for all valid inputs.