Add Lua 5.1 source files and documentation, including core libraries, interpreter, and test scripts.

ref/lua-5.1/etc/lua.hpp

@@ -0,0 +1,9 @@
+// lua.hpp
+// Lua header files for C++
+// <<extern "C">> not supplied automatically because Lua also compiles as C++
+
+extern "C" {
+#include "lua.h"
+#include "lualib.h"
+#include "lauxlib.h"
+}