Add support for building with lua 5.2.2

instead of luajit. There are some API compatibility macros
to be defined. The Makefile.PL tries to DRTR based on the
environment variables LUAJIT_DIR or LUA_DIR, but your
mileage may obviously vary.

NB. This patch is not enough to make all tests pass on
OSX, but at least lua is more friends with OSX than luajit.
Restore building with luajit
Build-system TODO

Conflicts:
	TODO
Port config script to use Alien::Lua

Rafael, if that breaks your OSX build, sorry! Try installing
Alien::Lua. If you are bold, you can try installing Alien::LuaJIT
on top of that which is going to be used by Alien::Lua by
default if it can.