support for lua keywords about code-prettify HOT 4 CLOSED

Note: This will break the tests for bash due to new "local" keywords

Here's the starter patch to support Lua.  I patched the bash block to handle 
the new
local keyword.  Only thing left to do is add test case.  HTML contains some 
test code
I snatched from http://lua-users.org/wiki for giggles.

Enjoy!

Note: I felt as if I needed to hack at the 'END'PLN blah tokens to make the 
test case
work, please let me know if it was all done correctly.

Since LUA has a very different lexical grammar than most of the other 
languages, I
did it as a language extension.  See the usage comment in
http://code.google.com/p/google-code-prettify/source/browse/trunk/src/lang-lua.j
s

Please also see the testcase at
http://google-code-prettify.googlecode.com/svn/trunk/tests/prettify_test.html#is
sue24

I've never written a line of LUA, so that's based on my quick reading of 
chapter 2 of
the language reference.  Please let me know if it's all mucked up.