Haskell Lua bindings, forked from Gracjan Polak's HsLua library.

• Use ByteString -- The Lua module sees extremely few uses of String now, aside from calls to error and in the instance for StackValue String.
• Change the module name from Scripting.Lua to Lua.
• Lots of refactoring...
• Support using the system's Lua installation instead of the bundled one, with the system-lua cabal flag.