metaprogramming links

[David Manura <dm.lua@...>]

Here's an initial compilation of links relating to the often discussed
topic of Lua metaprogramming (e.g. macros, token filters, facilities
for syntax extensions, and source processors).  Feel free to expand:

  http://lua-users.org/wiki/MetaProgramming