Utf8 Library

[Mike Nelson <mikestar1313@...>]

I've been playing around with the new utf8 library for Lua 5.3 work2 and 
find it quite useful. Nice work. I have backported it to Lua 5.2.3 and 
it seems to work fine there as well, though still testing at this point.

The C coding was simple enough for my C coding skills--messing with lua 
internals is the first C programming I've done since college.  I need to 
do some more testing to be sure everything is OK, but it looks good. I'm 
pretty busy right now, but should be able to post a proper diff in a few 
days.

-- Mike Nelson