New UTF-8 stride function

[Martin Nowak]

On 05/27/2013 09:21 PM, Martin Nowak wrote:
>  > See unittest/benchmark here:
>  > https://gist.github.com/blackwhale/5653927
>  >
> Looks promising.

This will not detect 0xFF as invalid UTF-8 sequence.
For sequences with 5 or 6 bytes, that aren't used for unicode, it will 
return a stride of 4.