lua branch

[Ian Price]

Prompted by the recent discussion of lua/zile on guile-user, I decided
to checkout what the actual state of the Lua branch is.

First off, not all of the tests pass.
- lua-standard-library and lua-eval pass with no problems.
- lua-lexer has 1 failure, which is easy fixed (change #:vararg
   to #:varargs)
- lua-eval-3 throws an error, and so the test doesn't finish running.
  The issue seems to be that the lua->tree-il conversion does not
  compile the <ast-variable-arguments> record. (Lua's '...').
- lua-eval-2 has a similar issue, but this only results in a failure,
  rather than an error.

The branch does not have any git issues with rebasing it onto a modern
stable-2.0 branch, however it does result in some new test failures,
indicating some reliance on changed behaviours.

I don't know much about Lua, but I think I could do the following.
1. Fix the lua-lexer failure.
2. Disable or fix[1] the variable-arguments functionality.
3. Rebase or merge with modern stable or master
4. Fix the errors that arise as a result of 3.

[1] I _think_ what needs done is just to compile it into a lexical
ref, but with some hacking to make sure that the code gets the right
gensym for the enclosing function's '...'. Right now, there is no way to
get that information.

-- 
Ian Price -- shift-reset.com

"Programming is like pinball. The reward for doing it well is
the opportunity to do it again" - from "The Wizardy Compiled"