Re: mathlib

Anyway, the first portability fix would be to make the same code compile 
against Lua 5.1 and 5.2 like a lot of other modules:
LUALIB_API int luaopen_mathx(lua_State *L)
{
#if LUA_VERSION_NUM <= 501
 luaL_register(L,LUA_MATHLIBNAME,R);
#else
 lua_getglobal(L,LUA_MATHLIBNAME);
 luaL_setfuncs(L,R,0);
#endif

For Visual Studio 2010 and 2012, the following warnings and errors are 
generated. I don't know what you would do to fix them.

If these compilers support C99 math functions then there is probably
a switch somewhere. Note how I've used
	#define _GNU_SOURCE 1
so that it works in Linux, which is probably not optimal but worked on
the systems I tested.